StemCell Therapy

The data accumulated by scientists of the early 20th century provided compelling evidence that chromosomes are the carriers of genes. But the nature of the genes themselves remained a mystery, as did the mechanism by which they exert their influence. Molecular geneticsthe study of the structure and function of genes at the molecular levelprovided answers to these fundamental questions.

In 1869 Swiss chemist Johann Friedrich Miescher extracted a substance containing nitrogen and phosphorus from cell nuclei. The substance was originally called nuclein, but it is now known as deoxyribonucleic acid, or DNA. DNA is the chemical component of the chromosomes that is chiefly responsible for their staining properties in microscopic preparations. Since the chromosomes of eukaryotes contain a variety of proteins in addition to DNA, the question naturally arose whether the nucleic acids or the proteins, or both together, were the carriers of the genetic information. Until the early 1950s most biologists were inclined to believe that the proteins were the chief carriers of heredity. Nucleic acids contain only four different unitary building blocks, but proteins are made up of 20 different amino acids. Proteins therefore appeared to have a greater diversity of structure, and the diversity of the genes seemed at first likely to rest on the diversity of the proteins.

Evidence that DNA acts as the carrier of the genetic information was first firmly demonstrated by exquisitely simple microbiological studies. In 1928 English bacteriologist Frederick Griffith was studying two strains of the bacterium Streptococcus pneumoniae; one strain was lethal to mice (virulent) and the other was harmless (avirulent). Griffith found that mice inoculated with either the heat-killed virulent bacteria or the living avirulent bacteria remained free of infection, but mice inoculated with a mixture of both became infected and died. It seemed as if some chemical transforming principle had transferred from the dead virulent cells into the avirulent cells and changed them. In 1944 American bacteriologist Oswald T. Avery and his coworkers found that the transforming factor was DNA. Avery and his research team obtained mixtures from heat-killed virulent bacteria and inactivated either the proteins, polysaccharides (sugar subunits), lipids, DNA, or RNA (ribonucleic acid, a close chemical relative of DNA) and added each type of preparation individually to avirulent cells. The only molecular class whose inactivation prevented transformation to virulence was DNA. Therefore, it seemed that DNA, because it could transform, must be the hereditary material.

A similar conclusion was reached from the study of bacteriophages, viruses that attack and kill bacterial cells. From a host cell infected by one bacteriophage, hundreds of bacteriophage progeny are produced. In 1952 American biologists Alfred D. Hershey and Martha Chase prepared two populations of bacteriophage particles. In one population, the outer protein coat of the bacteriophage was labeled with a radioactive isotope; in the other, the DNA was labeled. After allowing both populations to attack bacteria, Hershey and Chase found that only when DNA was labeled did the progeny bacteriophage contain radioactivity. Therefore, they concluded that DNA is injected into the bacterial cell, where it directs the synthesis of numerous complete bacteriophages at the expense of the host. In other words, in bacteriophages DNA is the hereditary material responsible for the fundamental characteristics of the virus.

Today the genetic makeup of most organisms can be transformed using externally applied DNA, in a manner similar to that used by Avery for bacteria. Transforming DNA is able to pass through cellular and nuclear membranes and then integrate into the chromosomal DNA of the recipient cell. Furthermore, using modern DNA technology, it is possible to isolate the section of chromosomal DNA that constitutes an individual gene, manipulate its structure, and reintroduce it into a cell to cause changes that show beyond doubt that the DNA is responsible for a large part of the overall characteristics of an organism. For reasons such as these, it is now accepted that, in all living organisms, with the exception of some viruses, genes are composed of DNA.

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Heredity - DNA, Genes, Inheritance | Britannica

When it comes to the study of genes, there are two different approaches that scientists use to gain a deeper understanding of genetic makeup and its role in various biological processes. These approaches are genetics and molecular genetics. While both involve the analysis and research of genetic material, there are significant differences between the two.

Genetics, as a field of study, focuses on the inheritance and variation of genes in organisms. It involves the examination of traits, such as eye color or height, and the mapping of these traits to specific genes. This approach involves studying the DNA sequences and chromosomes to understand how genes are passed down from one generation to another.

On the other hand, molecular genetics takes a more detailed and intricate look at genes and their functions. It delves into the molecular mechanisms behind genetic processes, such as DNA replication, transcription, and translation. Molecular genetics employs advanced techniques and tools to analyze the structure and function of genes at the molecular level, including the study of specific gene mutations that may cause diseases.

Therefore, the main difference between genetics and molecular genetics lies in their scope and depth of analysis. While genetics looks at the broader picture of gene inheritance and variation, molecular genetics zooms in to elucidate the complex molecular processes and interactions that occur within genes. Both disciplines are valuable in their own right, complementing each other to provide a comprehensive understanding of how genes function and contribute to the diversity of life on Earth.

In the study of genetics, two main approaches are often compared: genetics and molecular genetics. Although these terms may sound similar, they represent different fields of analysis and study.

Genetics is the branch of biology that focuses on the study of genes, heredity, and variation in living organisms. It involves the analysis of inherited traits and the passing of genetic information from one generation to the next. Geneticists use various techniques, such as pedigree analysis and population genetics, to understand how genes are inherited and how they contribute to the diversity of organisms.

Molecular genetics, on the other hand, takes a more detailed and specific approach. It focuses on the study of the structure, function, and organization of genes at a molecular level. Molecular geneticists use advanced techniques, such as DNA sequencing and gene cloning, to analyze the DNA molecules and understand how specific genes function and interact. They study the mechanisms of gene expression, regulation, and mutations, and how they relate to genetic disorders and diseases.

While genetics provides a broad overview of inherited traits and genetic patterns in populations, molecular genetics delves deeper into the molecular mechanisms that underlie these patterns. It is a more specialized field that allows for a more detailed understanding of how genes function and how they contribute to the diversity of life forms.

In summary, genetics and molecular genetics are two distinct but related fields of study. Genetics provides a broader analysis of inherited traits and genetic patterns, while molecular genetics takes a more specific approach in understanding the molecular mechanisms of genes. Both fields are crucial for advancing our knowledge of genetics and its impact on living organisms.

In the field of genetics, the study of inheritance and variation in living organisms has been a subject of fascination since ancient times. However, it wasnt until the mid-20th century that the field took a major leap forward with the advent of molecular genetics.

Prior to the emergence of molecular genetics, the study of genetics primarily focused on observing and analyzing the hereditary traits of organisms through methods such as breeding experiments, statistical analysis, and observation of visible characteristics. This approach, known as classical genetics, provided valuable insights into the patterns of inheritance but had limitations in its ability to interrogate the underlying molecular mechanisms.

Molecular genetics, on the other hand, revolutionized the field by introducing a more detailed and comprehensive approach to the study of genetics. This approach involved the exploration of the structure and function of genes at the molecular level, analyzing the role of DNA and RNA in gene expression, and understanding the mechanisms of mutation and genetic variation.

The comparison between classical genetics and molecular genetics reveals significant differences in their research methodology and analysis. Classical genetics relied on observational data and statistical analysis to infer patterns of inheritance, while molecular genetics employs sophisticated laboratory techniques to manipulate and analyze DNA and RNA molecules.

Furthermore, the advent of molecular genetics has allowed researchers to delve deeper into the intricate mechanisms of genetic inheritance and variation. By studying molecular processes such as DNA replication, transcription, and translation, scientists have gained a more nuanced understanding of how genes interact and contribute to the development and functioning of organisms.

Overall, the emergence of molecular genetics as a distinct discipline has greatly expanded our knowledge of genetics and opened up new avenues of research. Its focus on the molecular level has provided invaluable insights into the complexities of genetic processes and has paved the way for advancements in fields such as biotechnology, genomics, and personalized medicine.

When it comes to the study of genetics and molecular genetics, there are several key concepts to understand. A comparison between genetics and molecular genetics provides insights into the differences in their approaches and analysis.

Genetics is the study of genes and heredity. It focuses on the inheritance of traits from one generation to another. Geneticists analyze the variations and similarities in genes to understand how certain traits are passed on and expressed through generations. They study the genes at a macroscopic level, observing the patterns of inheritance and the effects of genetic mutations on individuals.

Molecular genetics, on the other hand, takes a more microscopic approach. It zooms in on the molecular level to understand the structure and function of genes. By analyzing DNA and RNA sequences, molecular geneticists can unravel the intricacies of genetic information. They study the changes and interactions within genes and delve deeper into the mechanisms of gene expression and regulation.

The main difference between genetics and molecular genetics lies in their level of analysis. Genetics takes a broader approach, while molecular genetics focuses on a more detailed examination of genes and their molecular components. Both fields contribute to the understanding of how genetic information is inherited and expressed, but they employ different methodologies and perspectives.

In conclusion, genetics and molecular genetics are two related fields that study genes and heredity. Genetics focuses on the inheritance of traits at a macroscopic level, while molecular genetics delves into the molecular components and mechanisms of gene expression. By understanding the differences between these two approaches, scientists can gain a more comprehensive understanding of the complexities of genetic information.

In the research field of genetics, the methodology often involves the study of genetic variations and heredity patterns in living organisms. This can be achieved through various techniques such as pedigree analysis, gene mapping, and DNA sequencing. The primary focus of genetic research is to understand the differences and similarities between individuals and populations in terms of their genetic makeup.

On the other hand, molecular genetics is a more specific branch of genetics that focuses on the analysis of DNA and RNA molecules. It involves studying the structure, function, and regulation of genes at a molecular level. Molecular geneticists use techniques like PCR (polymerase chain reaction), gel electrophoresis, and DNA cloning to isolate and analyze specific genes or DNA sequences.

One key difference between genetic research and molecular genetics is the scale at which they operate. While traditional genetics looks at broader genetic traits and inheritance patterns, molecular genetics examines the specific molecular mechanisms behind these traits. This enables researchers to gain a more in-depth understanding of the biological processes involved.

Another difference is the level of detail in the analysis. Genetic research often involves observations at the organism level, such as comparing traits between individuals or populations. In contrast, molecular genetics focuses on the molecular level, analyzing DNA sequences and gene expression patterns.

In summary, the comparison between genetics and molecular genetics reveals the differences in the scope and approach of the two fields. While genetics provides a broader perspective on heredity and genetic variation, molecular genetics delves into the intricate molecular mechanisms underlying these phenomena. Both disciplines contribute valuable insights to our understanding of the genetic basis of life.

Both genetics and molecular genetics have important applications in the field of medicine. While there are some differences in their approaches and methodologies, they both contribute to our understanding of genetic diseases and provide valuable insights for diagnosis, treatment, and prevention.

Genetics is the study of heredity and the variation of inherited traits in organisms. It focuses on the examination of genes, their structures, functions, and how they are transmitted from one generation to another. Genetic analysis has long been used in the medical field to identify the genetic basis of diseases and to assess an individuals risk for developing certain conditions. It has played a crucial role in the identification of genetic disorders, such as Down syndrome and cystic fibrosis. Genetic counseling, which involves assessing an individuals risk for genetic conditions and providing information and support, is another important application of genetics in medicine.

Molecular genetics, on the other hand, takes a more focused approach by studying the structure and function of individual genes at a molecular level. It involves the analysis of DNA, RNA, and proteins to understand how genes are regulated and how they contribute to the development of diseases. The molecular analysis of genes has revolutionized the field of medicine by enabling researchers to identify specific molecular markers for diseases, develop targeted therapies, and predict therapeutic responses. This approach has led to personalized medicine, where treatments can be tailored to an individuals genetic profile.

Both genetics and molecular genetics have contributed significantly to the understanding and treatment of genetic diseases. While genetics provides a broader picture of genetic inheritance and variation, molecular genetics offers a more detailed analysis of genes and their functions. Together, they form a powerful combination for medical research and have paved the way for breakthroughs in the diagnosis, treatment, and prevention of genetic disorders.

When it comes to the field of agriculture, both genetics and molecular genetics play crucial roles in research and advancements. While they may have similarities in their approaches and analyses, there are also significant differences between the two.

Genetics, as a branch of biology, studies the inheritance and variation of traits in living organisms, including plants and animals. In agriculture, genetics is applied to breed selectively and improve the desirable traits of crops and livestock. Through traditional breeding methods, geneticists identify and cross-breed plants and animals with specific desirable traits to create new varieties with enhanced characteristics such as disease resistance, productivity, and quality.

The Role of Molecular Genetics in Agriculture

Molecular genetics takes a more advanced and precise approach compared to traditional genetics. It involves the study of genes and their functions at the molecular level, focusing on analyzing DNA and other genetic materials.

Advancements in molecular genetics have revolutionized the field of agriculture.

While traditional genetics relies on breeding experiments and observations, molecular genetics utilizes various laboratory techniques and technologies to directly manipulate and analyze genetic materials. This includes techniques such as polymerase chain reaction (PCR), gene cloning, and genome sequencing.

Analysis and Study of Genes

Molecular genetics allows for a more in-depth analysis and study of individual genes, their interactions, and their functions. This provides valuable insights into the underlying genetic mechanisms responsible for specific traits in plants and animals, leading to a better understanding of their biology and potential for improvement.

The study of molecular genetics also enables the identification and characterization of genes associated with valuable traits in crops, such as drought tolerance, nutrient efficiency, and pest resistance.

By identifying and manipulating these genes, scientists can develop genetically modified organisms (GMOs) with enhanced traits, such as genetically modified crops with increased yield or improved nutritional content.

In conclusion, both genetics and molecular genetics have significant applications in agriculture. While traditional genetics focuses on selective breeding, molecular genetics allows for a more advanced and precise understanding and manipulation of genes. Together, these fields contribute to the development of improved crops and livestock for a more sustainable and efficient agricultural industry.

In the field of forensics, the study of genetics and molecular genetics has been instrumental in solving crimes and identifying individuals involved in criminal activities. Through the analysis of genetic material found at crime scenes, forensic scientists are able to compare and identify differences in the genetic profiles of suspects. This approach allows for a more reliable and accurate comparison of DNA samples, which is crucial in criminal investigations.

Molecular genetics, with its focus on the study of molecular structure and function, offers a more detailed and precise approach to forensic analysis. By examining specific genes and their variations, forensic scientists can establish a genetic profile of an individual, providing important clues in identifying suspects or victims.

Genetics, on the other hand, takes a broader perspective in the study of inherited traits and the genetic makeup of individuals. It involves the comparison of DNA sequences, studying inherited variations, and determining the likelihood of individuals carrying certain traits or diseases. In forensics, genetic analysis is crucial in establishing familial relationships, such as paternity or kinship, which can be helpful in suspect identification or victim identification.

By comparing the genetic profiles of individuals found at crime scenes with those in a database, forensic scientists can identify potential suspects or rule out individuals who may be wrongly implicated. This process involves a comprehensive analysis of DNA samples, including the identification of specific genetic markers that are unique to each individual.

While both genetics and molecular genetics play vital roles in forensic analysis, there are differences in their approaches and focus. Genetics offers a broader perspective on inherited traits, while molecular genetics provides a more detailed and in-depth analysis of genetic material. The comparison of genetic profiles and the identification of unique markers are common goals in both fields.

Overall, the study of genetics and molecular genetics is essential in forensic research and analysis. By using these approaches, forensic scientists are able to provide valuable evidence and insights in solving crimes, identifying suspects, and bringing justice to victims and their families.

In the study of genetics and molecular genetics, researchers employ different approaches and techniques to gain insights into the complex world of genes and their functions. The analysis of genetic information requires a combination of both genetic and molecular research methods.

Genetics research typically focuses on the inheritance and variation of genes among different individuals or populations. It often involves studying the physical traits, hereditary patterns, and genetic disorders in order to understand the role of genes in biological processes. Geneticists use various techniques such as pedigree analysis, linkage analysis, and genetic mapping to uncover the inheritance patterns of specific traits.

Molecular genetics, on the other hand, delves deeper into the molecular mechanisms behind genetic processes. This field employs advanced techniques to analyze DNA, RNA, and protein molecules. Researchers in molecular genetics use tools like polymerase chain reaction (PCR), DNA sequencing, and gene expression analysis to study the structure, function, and regulation of genes at the molecular level.

While genetics research focuses on broader patterns of inheritance and genetic variation, molecular genetics provides a more detailed understanding of the molecular events governing gene expression and regulation. Both approaches are crucial for unraveling the complexities of genetic information and its implications for health and disease.

In summary, genetics research and molecular genetics employ distinct research techniques to study genes and their functions. Genetics research takes a broader approach, focusing on inheritance patterns and genetic variation, while molecular genetics provides a deeper analysis of the molecular mechanisms behind genetic processes. Combining these two approaches enables researchers to gain a comprehensive understanding of genetics and its role in various biological processes.

The study of genetics and molecular genetics has had a significant impact on the field of evolutionary biology. By comparing the differences between genetic information and its molecular analysis, scientists have been able to gain a deeper understanding of the processes and mechanisms that drive evolution.

In traditional genetic study, scientists focus on the study of genes and their inheritance patterns within populations. This approach allows researchers to track the transmission of specific traits and determine how they are passed down through generations. However, this method does not provide detailed information about the molecular mechanisms that underlie genetic changes.

In contrast, molecular analysis takes a more detailed and precise approach. It involves the study of DNA and other molecules that make up the genetic material. Molecular techniques such as DNA sequencing, PCR, and gene expression analysis allow scientists to analyze the structure and function of genes at the molecular level. By understanding the molecular differences between individuals and species, researchers can gain insights into the evolutionary processes that shape biodiversity.

By combining the study of genetics with molecular analysis, scientists can compare genetic information across different species and populations. This comparative approach provides valuable insights into the evolutionary relationships between organisms and helps researchers reconstruct the evolutionary history of species.

Molecular genetics also allows researchers to study the impact of genetic variation and genetic changes on evolution. By analyzing DNA sequences, scientists can identify mutations and other genetic changes that occur over time. These studies help researchers understand the mechanisms of adaptation, speciation, and genetic drift, all of which play crucial roles in shaping evolution.

In summary, the integration of genetics and molecular analysis has revolutionized the field of evolutionary biology. This interdisciplinary approach provides researchers with a powerful tool to decipher the genetic and molecular basis of evolutionary processes. By understanding the impact of genetic variation and molecular differences, scientists can gain a deeper understanding of how species evolve and adapt in response to their changing environments.

In the field of genetics, the role of molecular genetics plays a crucial part in the process of genetic counseling. Genetic counseling aims to provide individuals and families with accurate information about the risk of genetic conditions and to support them in making informed decisions about their health and reproduction.

Molecular genetics involves the analysis of DNA, genes, and chromosomes to understand the underlying causes of genetic disorders. This study uses a different approach compared to traditional genetics, which focuses on studying the observable differences and traits in individuals.

One of the key roles of molecular genetics in genetic counseling is to analyze genetic variations that may contribute to an individuals risk of developing a genetic condition. Through advanced research techniques and technologies, molecular geneticists can identify specific changes in an individuals DNA sequence that could be associated with inherited diseases.

This analysis helps genetic counselors provide accurate information about the chances of the condition being passed on to future generations, providing individuals with a better understanding of their genetic risks. With this information, individuals can make informed decisions about family planning, reproductive options, and potential medical interventions.

Another important aspect of molecular genetics in genetic counseling is the comparison of DNA sequences. By comparing DNA sequences of individuals with and without certain genetic conditions, researchers can identify genetic variations that may contribute to the development of these disorders.

Comparative analysis helps in the early detection, diagnosis, and treatment of various genetic conditions, allowing individuals and families to access appropriate medical care and support. This approach enables genetic counselors to provide personalized genetic counseling, tailoring their recommendations and support based on the specific genetic profile of each individual.

Conclusion

The role of molecular genetics in genetic counseling is essential for understanding the underlying genetic factors contributing to inherited diseases. By analyzing genetic variations and comparing DNA sequences, molecular genetics provides valuable information that can guide individuals and families in making informed decisions about their health and reproduction. Through this approach, genetic counseling becomes more accurate, personalized, and effective in supporting individuals and families.

The comparison between genetics and molecular genetics in the context of disease diagnosis is crucial for understanding the approach and differences in the analysis of genetic disorders.

Genetics, as a field of study, focuses on the inheritance and variation of genes in organisms. It examines the role of genes in transmitting traits, including disease susceptibility. Genetic analysis involves studying the genetic makeup of individuals to identify mutations or alterations in specific genes that may contribute to the development of diseases.

In disease diagnosis, the study of genetics plays a significant role. Genetic tests can determine the presence or absence of specific genes associated with certain diseases. These tests help identify individuals who may be at risk or carriers for genetic disorders. Genetic counseling based on these findings can aid in making informed decisions about treatment options or preventive measures.

Traditional genetics primarily focuses on the study of inherited diseases caused by mutations in specific genes. It involves analyzing the presence of these mutations within families or populations to understand the pattern of disease transmission. This information is valuable in identifying affected individuals, predicting disease outcomes, and providing appropriate interventions.

Molecular genetics takes a more detailed and advanced approach to disease diagnosis compared to traditional genetics. It involves analyzing the structure and function of genes at a molecular level, including DNA sequencing and gene expression studies. The study of molecular genetics allows for a deeper understanding of the underlying mechanisms behind the development and progression of genetic disorders.

Molecular genetic analysis can identify specific genetic mutations or alterations that may contribute to disease susceptibility. It provides insights into the molecular pathways involved in disease development, allowing for targeted therapies and personalized treatment approaches. This approach also enables the identification of potential therapeutic targets and the development of novel treatment strategies.

In conclusion, both genetics and molecular genetics play essential roles in disease diagnosis. While genetics focuses on the inheritance and variation of genes, molecular genetics provides a more detailed analysis at the molecular level. Understanding the differences between these approaches is crucial for advancing our knowledge of genetic disorders and improving disease diagnosis and treatment.

In drug development, both genetics and molecular genetics play an important role in understanding the mechanisms of action of drugs and their potential effects on individuals. However, there are some differences in their approach and focus on research and study.

Genetics: a field of study that focuses on the inheritance and variation of genes in individuals and populations. It explores how genes influence the development, functioning, and characteristics of organisms. In drug development, genetics research aims to identify genetic variations that may affect the response to drugs, such as the presence of specific genes associated with drug metabolism or drug targets.

Molecular Genetics: a subfield of genetics that involves the study of DNA, RNA, and other molecules involved in genetic information and gene expression. It focuses on understanding the molecular mechanisms underlying various genetic processes, such as DNA replication, gene transcription, and protein synthesis. In drug development, molecular genetics research aims to unravel the molecular pathways and targets that drugs interact with in order to develop more targeted and effective treatments.

While genetics provides a broader perspective on the influence of genes on drug response and potential side effects, molecular genetics delves deeper into the specific molecular mechanisms through which drugs exert their effects. By combining the knowledge gained from genetics and molecular genetics, researchers can better understand the genetic basis of diseases and tailor drug therapies to individual patients.

By comparing the genetic profiles of patients who respond well to a drug with those who do not, researchers can identify genetic markers that predict drug response. This information can then be used to develop diagnostic tests that help identify individuals who are more likely to benefit from a particular drug or who may experience adverse reactions. Additionally, the study of molecular genetics can uncover new drug targets and pathways that can be exploited for drug development.

When comparing genetics and molecular genetics, it is important to consider the ethical implications of both approaches. While genetics is the study of genes and heredity, molecular genetics takes a more focused and analytical approach by examining the structure and function of genes at a molecular level. This difference in approach can lead to different ethical considerations in research and analysis.

In genetics, ethical considerations often revolve around issues such as privacy and informed consent. Researchers may need to handle sensitive information related to an individuals genetic makeup, which raises concerns about data privacy and confidentiality. Additionally, when conducting genetic studies, informed consent from participants is crucial to ensure that they fully understand the risks and benefits of participating in the research.

There is also the issue of genetic discrimination, where individuals may face discrimination based on their genetic information. This can have significant social and psychological impacts, highlighting the need for policies and laws to protect individuals from such discrimination.

In molecular genetics, ethical considerations are more focused on the research and analysis techniques used. Molecular genetics often involves the manipulation and modification of genetic material in a laboratory setting. This raises concerns about the potential risks and consequences of such manipulations. It is important to ensure that these techniques are conducted safely and in accordance with ethical guidelines to minimize any harm to both humans and other organisms.

Furthermore, the use of genetically modified organisms (GMOs) in molecular genetics research also raises ethical concerns. GMOs can have ecological implications and may raise questions about the potential long-term effects on the environment and other organisms.

In conclusion, while both genetics and molecular genetics share similarities in their study of genes, they have different approaches that can lead to distinct ethical considerations. Understanding and addressing these ethical concerns is essential to ensure the responsible and ethical advancement of genetic and molecular genetics research.

The analysis of genetics and molecular genetics is a field of research and study that poses several challenges for scientists. Both approaches involve the study of genes and the hereditary material, but they differ in their methodologies and scope. Understanding these challenges is crucial for advancing our knowledge in genetics and molecular genetics.

One of the current challenges in the field of molecular genetics is understanding the complexity of the molecular mechanisms that govern gene expression and regulation. Molecular genetics focuses on studying the individual molecules, such as DNA, RNA, and proteins, that make up the genetic material. This approach requires advanced techniques and technologies to analyze and manipulate these molecules, as well as computational methods to interpret the vast amount of data generated. The complexity of these molecular interactions presents a challenge for researchers in understanding the underlying mechanisms that control gene expression.

Another challenge in genetics and molecular genetics is the comparative analysis of data obtained from different organisms. While genetics traditionally involves studying specific traits and genes within a particular species, molecular genetics allows for a broader comparison across species. However, comparing genetic information between organisms can be difficult due to variations in gene structure, gene function, and regulatory mechanisms. Researchers need to develop standardized approaches and tools to compare and analyze genetic data from diverse organisms, which can help identify common patterns and evolutionary relationships.

In conclusion, the study of genetics and molecular genetics faces various challenges. The molecular complexity of gene regulation and expression requires advanced techniques and computational methods. Additionally, the comparative analysis of genetic data across different organisms calls for standardized approaches and tools. Overcoming these challenges is essential for advancing our understanding of genetics and molecular genetics and their applications in various fields, including medicine and agriculture.

The study of genetics and molecular genetics has provided valuable insights into the complexities and mechanisms of inheritance and genetic variation. However, there is still much to be discovered and understood in these fields. As technology continues to advance, new approaches and techniques are being developed that will further enhance our understanding of genetics.

One future direction is the use of comparative analysis to deepen our understanding of genetics. By comparing the genomes of different organisms, scientists can identify similarities and differences in their genetic makeup. This comparative approach allows for a more comprehensive understanding of how genetics shape biological traits and functions.

Furthermore, comparative analysis can help us uncover the evolutionary relationships between species. By examining the similarities and differences in their genetic information, scientists can reconstruct the evolutionary history of different organisms, shedding light on how life has evolved over millions of years.

Another future direction is the integration of molecular and genetic approaches. While genetics focuses on the study of inheritance and variation at the organismal level, molecular genetics delves into the underlying molecular mechanisms that drive these processes.

By combining these two approaches, researchers can gain a more comprehensive understanding of the genetic basis of traits and diseases. Molecular genetics provides the tools and techniques to examine the specific genes and molecules involved, while genetics provides the broader context and understanding of how these genes and molecules interact within an organism.

This integration of molecular and genetic approaches will allow for a more nuanced and sophisticated analysis of genetic variation and inheritance, providing valuable insights into the differences and similarities between individuals and populations.

In conclusion, the future of genetics and molecular genetics lies in the continued exploration of comparative analysis and the integration of molecular and genetic approaches. These advancements will further enhance our understanding of the complexities of genetics and pave the way for breakthroughs in fields such as personalized medicine and genetic engineering.

In the field of genetics, data analysis plays a crucial role in understanding the complexities of genetic information. Both genetics and molecular genetics employ different approaches in the study of genes and genetic variations.

In traditional genetics, the analysis focuses on studying traits and heredity patterns within populations or families. It involves observing and quantifying physical characteristics, as well as tracking the inheritance of specific traits through generations. This approach relies on family trees, Punnett squares, and statistical methods to analyze the data.

On the other hand, molecular genetics takes a more detailed and precise approach in analyzing genetic data. It involves studying the structure and function of DNA, genes, and proteins at the molecular level. This field has revolutionized the study of genetics by introducing techniques such as DNA sequencing and polymerase chain reaction (PCR).

Molecular genetics uses advanced laboratory techniques to isolate, amplify, and analyze specific regions of DNA. This allows researchers to identify and study genetic variations, mutations, and gene expression patterns. Data analysis in molecular genetics often involves complex algorithms, bioinformatics tools, and statistical methods.

By comparing genetics and molecular genetics, it becomes evident that the main difference lies in the level of detail and precision in data analysis. Traditional genetics provides a broader perspective on genetic traits and inheritance patterns, while molecular genetics offers a deeper understanding of the molecular mechanisms underlying genetic variations and gene functions.

Overall, the comparison between genetics and molecular genetics highlights the evolving nature of genetic studies. While both approaches contribute to our understanding of genes and heredity, molecular genetics allows for a more in-depth analysis of genetic data, paving the way for new discoveries and advancements in the field.

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Comparing Genetics and Molecular Genetics: What's the Difference?

The American College of Medical Genetics and Genomics (ACMG) previously developed guidance for the interpretation of sequence variants.(1) In the past decade, sequencing technology has evolved rapidly with the advent of high-throughput next-generation sequencing. By adopting and leveraging next-generation sequencing, clinical laboratories are now performing an ever-increasing catalogue of genetic testing spanning genotyping, single genes, gene panels, exomes, genomes, transcriptomes, and epigenetic assays for genetic disorders. By virtue of increased complexity, this shift in genetic testing has been accompanied by new challenges in sequence interpretation. In this context the ACMG convened a workgroup in 2013 comprising representatives from the ACMG, the Association for Molecular Pathology (AMP), and the College of American Pathologists to revisit and revise the standards and guidelines for the interpretation of sequence variants. The group consisted of clinical laboratory directors and clinicians. This report represents expert opinion of the workgroup with input from ACMG, AMP, and College of American Pathologists stakeholders. These recommendations primarily apply to the breadth of genetic tests used in clinical laboratories, including genotyping, single genes, panels, exomes, and genomes. This report recommends the use of specific standard terminology-"pathogenic," "likely pathogenic," "uncertain significance," "likely benign," and "benign"-to describe variants identified in genes that cause Mendelian disorders. Moreover, this recommendation describes a process for classifying variants into these five categories based on criteria using typical types of variant evidence (e.g., population data, computational data, functional data, segregation data). Because of the increased complexity of analysis and interpretation of clinical genetic testing described in this report, the ACMG strongly recommends that clinical molecular genetic testing should be performed in a Clinical Laboratory Improvement Amendments-approved laboratory, with results interpreted by a board-certified clinical molecular geneticist or molecular genetic pathologist or the equivalent.

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Standards and guidelines for the interpretation of sequence ... - PubMed

Genetics is the study of the inheritance and variation of biological traits. We have previously noted that it is possible to conduct genetic research without directly studying DNA. Indeed some of the greatest geneticists had no special knowledge of DNA at all, but relied instead on analysis of phenotypes, inheritance patterns, and their ratios in carefully designed crosses.

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Chapter 12: Techniques of Molecular Genetics - Biology LibreTexts

macromolecules

lysis

detergent

chelating agent

EDTA

nuclease

pellet

PCR

primer

thermalcycle

denature

anneal

extend

Taq DNApol

electrophoretic gel

restriction endonuclease

EcoRI

sticky end

blunt end

compatible end

ligation

ligase

plasmid

transformation

competent

electroporation

selectable marker

agarose

vector

band

ethidium bromide

Southern blot

membrane

denaturation

hybridization

washing

probe

stringency

northern blot

western blot

transgene

GMO

transformation

transfection

naked DNA

vector

electroporation

microinjection

vesicles

callus

knock-out

recalcitrant

Agrobacterium

particle bombardment

T-DNA

Ti plasmid

position effects

stem cells

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8.S: Techniques of Molecular Genetics (Summary)

The Master of Science in Computational Biology and Quantitative Genetics is designed to provide you with the statistical skills required to appropriately analyze large quantitative datasets as well as the epidemiological skills necessary to design, conduct, and evaluate experiments.

You will receive training in quantitative methods, including linear and logistic regression, survival analysis, longitudinal data analysis, statistical computing, clinical trials, statistical consultation and collaboration, and epidemiology. You will also gain a strong foundation in modern molecular biology and genetics, computer programming, the use and application of tools for analysis of genomic data, methods for integrative analysis, and meta-analysis of genes and gene function.

The program is intended as a terminal professional degree that enables you to launch your career in bioinformatics. It can also provide the foundation for further doctoral studies in biostatistics, epidemiology, computational biology, and other related fields.

On Campus (Fall start) Full-time (2 years)

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Master of Science Computational Biology and Quantitative Genetics

Pitt Researchers Lead Group that Calls for Global Discussion About Possible Risks from Mirror Bacteria  Pitt Health Sciences

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Pitt Researchers Lead Group that Calls for Global Discussion About Possible Risks from Mirror Bacteria - Pitt Health Sciences

Continuing Education Activity

Molecular diagnostics encompasses the analysis of human, viral, and microbial genomesand the products they encode. Molecular genetics utilizesmolecular biology's laboratory tools to relate genetic structureto protein function and, ultimately, health and disease.Variants identified during genetic testing are classified based on diverse evidence types, as the American College of Medical Genetics and Genomics recommends, emphasizing the need for board-certified geneticists to interpret the results.Integrating genetic testing methodologies with clinical expertise is crucial in translating molecular genetics advancements tobetter patient care.

The field of molecular genetic and genomic testing is undergoing rapid change due to improvements in our understanding of the molecular causes of uncommon and common illnesses and DNA analysis technologies.The advent of molecular genetics has revolutionized healthcare by offering unprecedented insights into the genetic basis of diseases, enabling personalized diagnostics, treatment strategies, and risk assessments. However, this progress brings with it the responsibility for healthcare providers to stay updated with the latest advancements and best practices in genetic testing.

This activity for healthcare professionals is designed to enhance learners' proficiency in identifying patients withindications for molecular genetics testing and interpreting genetic test results. Participants acquire a broader grasp of specimen collection, procedures, indications, potential diagnosis, normal and critical findings, interfering factors, and complications. Learners gain insights into thecomplexities of molecular genetics, preparing them to collaborate with an interprofessional team that aims to improve outcomes for patients who need molecular genetics testing.

Objectives:

Identify clinicalencounters appropriate for genetic molecular testing, distinguishing cases where such testing can contribute to diagnosis, prognosis, or treatment decisions.

Evaluate genetic test results accurately, discerning their clinical significance and relevance to patient management.

Differentiatebetween genetic testing methodologies, understanding their strengths, limitations, and optimal applications to diagnose patients.

Implement best interprofessional collaboration and communication practices to ensure that patientswho need molecular genetics testing receive comprehensive care that considers their medical, psychological, and social needs, thus improving outcomes.

Molecular genetics testing is fundamental in evaluating inherited disorders, somatic or acquired diseases with genetic associations, and pharmacogenetic responses. Genotyping can provide valuable disease diagnosis, prognosis, and progression indicators, guide treatment selection and response, and identify gene-specific therapeutic targets.[1]Human genetic material primarily consists of double-stranded, helical DNA. This molecule has a backbone composed of alternating sugar (deoxyribose) and phosphate groups, with hydrogen bonds linking nitrogenous base pairs. Specifically, adenine (purine) pairs with thymine (pyrimidine), while guanine (purine) pairs with cytosine (pyrimidine), forming the complementary base pairs within the DNA double helix.[2][3]

DNA in human cells is wrapped around histone proteins and packaged into nucleosome units, compacted further to form chromosomes.[4]Somatic cells normally have 23 chromosome pairs, with 1 pair comprised of the sex chromosomes X and Y. Each chromosome has DNA with a terminal stretch of short repeats called telomeres and additional repeats in the centromere region.[5]

Humans have 2 sets of 23 chromosomes, one derived from the mothers egg and the other from the father's sperm. Therefore, each egg and sperm is a single or haploid set of 23 chromosomes. Combining the 2 creates a diploid set of human DNA, allowing each individual to possess 2 different sequences, genes, and alleles on each chromosome.[6]Homologous recombination during meiosis generates unique allele combinations in gametes, leading to genetic diversity among offspring in the human population.[7]

The complete decoding of the human genome sequence and the development of powerful identification and cloning methods for genes linked to inherited diseases have transformed the practice of molecular genetics and molecular pathology. Advanced molecular analysis methods can now determine presymptomatic individuals' illness risk, detect asymptomatic recessive trait carriers, and prenatally diagnose conditions not yet evident in pregnancy.[8]Molecular genetics techniques are often the only approaches to these puzzles. Thus, genetic tests are powerful tools for diagnosis, genetic consultation, and prevention of heritable diseases.[9]

Many genetic testscan analyze gene, chromosome, and protein alterations. A clinician often considers several factors when selecting the appropriate test, including suspected conditions and their possible genetic variations. A broad genetic test is employed when a diagnosis is uncertain, while a targeted test is preferred for suspected specific conditions.[10]Molecular tests look for changes in 1 or more genes. These tests analyze the sequence of DNA building blocks (nucleotides) in an individual's genetic code, a process known as DNA sequencing, which can vary in scope.[11]

The targeted single variant test identifies a specific variant in a single gene known to cause a disorder, eg, the HBB gene variant causing-globin abnormalities that give rise to sickle cell disease. This test assesses the family members of an individual with the known variant to ascertain if they have the familial condition.[12]Single-gene tests examine genetic alterations in 1 gene to confirm or rule out a specific diagnosis, notably when many variants in the gene can cause the suspected condition. Gene panel tests look for variants in multiple genes to pinpoint a diagnosis when a person has symptoms that may fit various conditions or when many gene variants can cause the suspected condition.[13][14]

Whole-exome sequencing or whole-genome sequencing tests analyze the bulk of an individual's DNA to find genetic variations. This approach is useful when a single-gene or panel testing has not provided a diagnosis or when the suspected condition or genetic cause is unclear.[15]This sequencing method is often more cost- and time-effective than performing multiple single gene or panel tests.[16]

Chromosomal tests analyze whole chromosomes or long DNA lengths to identify significant alterations, including extra or missing chromosome copies (trisomy or monosomy), large chromosomal segment duplications or deletions, and segment rearrangements (translocations) (see Image. Trisomy 21on G-Banded Chromosomal Studies).[17]Chromosomal tests are employed when specific genetic conditions linked to chromosomal changes are suspected. For instance, Williams syndrome results from deleting a chromosome 7 segment.

Gene expression tests assess gene activation status in cells, indicating whether genes are active or inactive, with activated genes producing mRNA molecules that serve as templates for protein synthesis.[18]The mRNA produced helps determine which genes are highly active. Too much activity (overexpression) or too little activity (underexpression) of specific genes may suggest particular genetic disorders, including various cancer types.[19]Biochemical tests assess protein or enzyme levels and activity rather than directly analyzing DNA.[20]Abnormalities in these substances may indicate DNA changes underlying a genetic disorder.

Heritable mutations are detectable in all nucleated cells and are thus considered germline or constitutional genetic changes. Somatic genetic changes are characteristic of acquired or sporadic diseases like cancer.[21]Both scenarios are investigated using similar molecular biology methods to detect DNA and RNA variations, although the interpretation and utility of the laboratory results often differ significantly.[22]

Fluorescent in situ hybridization (FISH), chromosomal microarray analysis (CMA), and cytogenetic analysis (karyotyping) can be used to detect gross mutations like whole- and large-scale gene deletions, duplications, or rearrangements. Conventional karyotyping identifies rearrangements over 5 DNA megabases.[23]FISH has a resolution of 100 kilobases to 1 megabase. Minor alterations, such as single-base substitutions, insertions, and deletions, are detectable with single-strand conformation polymorphism (SSCP) and sequence analysis through next-generation sequencing (NGS). NGS uses genomic DNA (gDNA) or complementary DNA (cDNA) and has 3 modalities: whole genomic DNA, targeted, and exome sequencing.[24]

Denaturing high-performance liquid chromatography (DHPLC) can detect small deletions and duplications. Multiplex ligation-dependent probe amplification (MLPA) extends the range of deletions and duplications detected, bridging the gap between FISH or cytogenetic analysis and HPLC. MLPA is particularly useful in identifying complete or single and multiexon deletions or duplications.[25][26]

Peripheral blood is the specimen required for FISH, MLPA, DHPLC, and sequencing.Amniotic fluid cells and, more recently, cell-free fetal DNAmay be used for noninvasive prenatal testing.[27]Ethylenediaminetetraacetic acid is the most commonly used anticoagulant for molecular-based testing. However, acid citrate dextrose (ACD) is an acceptable alternative in cases where cellular form and function must be preserved.

ACD A and ACD B are the only ACD tube designations recognized, differing only by their additive concentrations.[28]Both enhancewhite blood cell viability and recovery for several days after specimen collection, making them suitable for molecular diagnostic and cytogenetic testing.

FISH utilizes fluorescent DNA probes to target specific gene sequences in interphase or metaphase cells, enabling their visualization and detection. Housekeeping gene probes always serve as positive internal controls. The probe must be large enough to hybridize specifically with the target without impeding the hybridization process. Conventional FISH involves pipetting the hybridization mix onto the cytological sample and incubating them together.

The technique can be applied to suspended cells, cultured cells, and frozen or formalin-fixed paraffin-embedded tissue sections, with subsequent cell sorting for fluorescence signal separation.[29]Preserving nucleic acid integrity and cell morphology is necessary during sample fixation. The experimental FISH procedure includes several preparatory steps, the hybridization reaction itself, and the removal of unbound probes.[30]The probe may be directly labeled with fluorophores or targeted for fluorescent detection using labeled antibodies or similar substrates. Different tags may be used, and different targets may be detected in the same sample simultaneously (multi-color FISH). Tagging is performed in various ways, including nick translation or polymerase chain reaction (PCR) using tagged nucleotides (see Image. Polymerase Chain Reaction). Probes can vary from 20 to 30 nucleotides to much longer sequences.

Locus-specific probes provide insight into gene amplification, deletion, or normal copy number status. Dual-fusion probes are adept at identifying frequently translocated gene regions associated with cancer development. These probes target regions spanning the breakpoints of translocation partners. Intact green and red signals are determined when they are closer than one signal's width. Conversely, a break in the gene sequence results in separate green and red signals.[31]

Break-apart probes target 2 areas of a specific gene sequence, using a green fluorescent label on one end and a red fluorescent label on the other. Intact gene sequences typically produce a yellow signal, known as a fusion signal. Whole-chromosome probes consist of smaller probes, each binding to different sequences along a chromosome.[32]Multiple probes, labeled with fluorescent dyes, enable unique color labeling of each chromosome, creating a spectral karyotypea full-color chromosome map identifyingall chromosome pairs.[33]Whole-chromosome probes are useful for examining chromosomal abnormalities, such as translocations.

Chromosomal microarray (CMA) consists of thousands of tiny probes, each representing small DNA fragments from known locations on the 46 chromosomes. CMA detects imbalances in chromosomal material between patient and control DNA samples, identifying copy number differenceswhether gains (duplications) or losses (deletions)in specific DNA segments.[34]These differences pinpoint the cause of the patient's health condition based on the location and type of change detected.[35]

Denaturing high-performance liquid chromatography (DHPLC) relies on differential chromatography retention of DNA heteroduplexes post-denaturation and renaturation. DNA heteroduplex migration is influenced by both molecule length and melting temperature, which is crucial for test sensitivity. DHPLC typically compares 2 PCR products amplified from 2 genes: 1 wild type and 1 mutated. These PCR products can originate from either RNA (cDNA) or genomic DNA. The PCR products are denatured at 95 C and gradually reannealed by cooling from 95 C to 65 C before chromatography. A major advantage of this technology is that multiple samples can be pooled together for variant detection.[36]Sequencing detects single-base substitutions and small deletions and insertions in DNA fragments ranging from 80 to 1500 base pairs, with close to 100% accuracy within minutes.

When a mismatch is present, both the original homoduplexes and 2 heteroduplexes are simultaneously produced. The original homoduplexes form from the reannealing of perfectly matching sense and antisense strands (25% each). The heteroduplexes form from the reannealing of the sense strand of one homoduplex with the antisense strand of the other (also 25% each). Heteroduplexes denature more extensively than homoduplexes, resulting in earlier elution from the chromatography column. The separation of all 4 species is based on their differences in stacking interactions with the chromatography column (solid phase). More detailed theoretical explanations of DHPLC are available in the literature.[37]

MLPA utilizes genomic DNA samples, with specific MLPA probes hybridizing with denatured genomic DNA. These probes are uniquely designed to hybridize adjacent to each other on the target DNA region and confer a distinct length to each amplified MLPA probe pair. Detection and quantification occur via capillary electrophoresis.[38]All MLPA probes are amplified using the same primer pair, with the abundance of each fragment proportional to its target's copy number in the sample.

NGS amplifies DNA with random priming, providing a genome-wide view of the patient's genetic background through millions of reads. Library generation begins with nucleic acid fragmentation, representing the individual's entire genome or transcriptome. Whole-exome sequencing uses cDNA fragments, whereas the whole-genome modality includes complete genomic DNA. Fragments join using enriched sequence adaptors. Only some genes (gene panel) are analyzed in targeted libraries. Fragments hybridize with cDNA fragments for the region or genes of interest and are specifically enriched.[39]During sequencing, nucleotide addition is detected by fluorescent dyes or pH changes from hydrogen ion release during DNA polymerization.[40]

Sanger sequencing begins with PCR-based target DNA amplification, followed by removing excess deoxynucleotide triphosphates (dNTPs) and PCR primers. The Sanger method has 99.99% base accuracy and is thus the "gold standard" for validating DNA sequences, including those from NGS. The test's stepsinclude denaturing the double-stranded DNA (dsDNA) into 2 single-stranded DNA (ssDNA), attaching a primer corresponding to one end of the sequence, and sequencing 4 polymerase solutions with 4 dNTPs. Only one type of ddNTP is incorporated, initiating DNA synthesis until termination. The resulting DNA fragments are denatured into ssDNA.

Denatured fragments undergo gel electrophoresis for sequence determination. DNA polymerase synthesizes DNA only in the 5 to 3 direction, initiating at a provided primer. Each terminal ddNTP corresponds to a specific nucleotide in the original sequence. For example, the shortest fragment must terminate at the first nucleotide from the 5 end, the second-shortest fragment must terminate at the second nucleotide from the 5 end, and so on. Reading gel bands from smallest to largest reveals the 5 to 3 sequence of the original DNA strand.[41]

In manual Sanger sequencing, the user reads all 4 gel lanes simultaneously, moving from bottom to top to identify the terminal ddNTP for each band. For instance, if the bottom band is found in the ddGTP column, then the smallest PCR fragment terminates with ddGTP, and the first nucleotide from the 5 end of the original sequence has a guanine (G) base.[42]Automated Sanger sequencing employs a computer to read each capillary gel band sequentially, using fluorescence to determine the terminal ddNTP identity. Laser activation of fluorescent tags emits light, detected by the computer, with each ddNTP tagged with a unique fluorescent label. The output is a chromatogram displaying fluorescent peaks corresponding to each nucleotide along the template DNA's length.[43]

Third-generation sequencing enables sequencing long DNA or RNA stretches without fragmentation. Single strands of DNA or RNA are directed through protein nanopores, with nucleotide bases distinguished by characteristic changes in electric current to determine the sequence.[44]Compared to 2nd-generation sequencing, 3rd-generation sequencing requires minimal sample preprocessing, enabling the design of smaller and more portable equipment.[45]

Molecular genetic testing has distinct indications, differing from traditional clinical and molecular biological testing used for diagnosing other diseases.[46]This modalitys applications encompass newborn screening, diagnostic testing for genetic or chromosomal conditions, carrier testing, prenatal testing, predictive and presymptomatic testing for adult-onset disorders, and forensic testing for legal identification purposes.[47]

FISH is employed for patients with a family history of known deletions and has been utilized to detect deletions in single blastomeres during preimplantation genetic diagnosis. FISH tests use gene-specific probe panels to investigate deletions, amplifications, and translocations in hematologic and solid tumors. FISH can also identify intracellular microorganisms and parasites.

CMA is recommended for individuals lacking specific clinical indicators to identify genetic or nongenetic causes of intellectual disability, developmental delay, autism spectrum disorder, or multiple congenital anomalies.[48]CMA can be helpful if prenatal structural anomalies are linked to particular microdeletions or microduplications. This modality can also evaluate copy number variants in cases of de novo balanced rearrangements or marker chromosomes.[49]

MLPA has diverse applications, such as mutation detection, single nucleotide polymorphisms (SNP) analysis, DNA methylation analysis, mRNA quantification, chromosomal characterization, gene copy number detection, and identification of duplications and deletions in cancer predisposition genes like BRCA1, BRCA2, hMLH1, and hMSH2. MLPA also holds promise for prenatal diagnosis, both invasive and noninvasive.[50]

DHPLC is well-suited for scanning genes for novel mutations and analyzing large sample sizes cost-effectively. This test is also useful for genotyping specific mutations or polymorphisms. DHPLC offers various applications beyond detecting genetic variants, including size-based double-strand DNA separation, single-strand DNA separation, and DNA purification analysis.[51]

NGS rapidly sequences whole genomes and target regions, employs RNA sequencing to identify novel RNA variants and splice sites, quantifies mRNAs for gene expression analysis, and analyzes epigenetic factors like DNA methylation and DNA-protein interactions. Sequence cancer samples study rare somatic variant tumor subclones and identify novel pathogens. Sanger sequencing, or the "chain termination method," determines DNA nucleotide sequences.

FISH swiftly diagnoses common fetal aneuploidies but with reduced sensitivity compared to cytogenetic analysis. FISH cannot identify cytogenetic abnormalities beyond the most common ones, such as translocations, inversions, and markers. DHPLC detects single nucleotide changes, small deletions, or insertions requiring subsequent confirmation by sequencing. This method identifies unknown mutations, making it advantageous for diseases with a high proportion of de novo mutations. Neurofibromatosis type 1 (NF1) is an example, as approximately 50% of cases arise from new mutations. CMAs are first-tier tests for developmental delays, intellectual disabilities, autism spectrum disorders, or multiple congenital disabilities, replacing karyotyping.

MLPA detects gene abnormalities, particularly small deletions in diseases like multiple endocrine neoplasia type 1 (MEN1partial or complete deletion). MLPA can also assess methylation alterations, such as in pseudohypoparathyroidism 1b (PHP1b), where deletion of 1 or 4 of four differentially methylated regions is common.

NGS generates millions of sequences, which are then processed, analyzed, and interpreted to identify variants. Bioinformatics analysis begins with raw data generated by nucleotide incorporation signal detection. Read quality is evaluated during primary data analysis. Sequences are aligned or mapped against a reference genome, with computational algorithms searching for the best match for each read while allowing for some mismatches to detect genetic variants.[52]

Sanger sequencing is reliable in detecting point mutations, small deletions, or duplications. This method has a long history of use across various settings, including tumor mutational spectrum analysis and diagnostic testing for constitutional variants. Primers can cover multiple regions (amplicons) or any desired region size.

The increasing demand for genetic testing has led to greater availability. Ensuring uniformity and standardization in communicating the complex results to referring clinicians is essential. Failure to include pertinent information is considered a deficiency in the molecular pathology laboratory accreditation inspection.[53]All molecular genetic laboratories offering clinical testing should be accredited according to the Clinical Laboratory Improvement Amendments and actively participate in proficiency testing.[54]

A comprehensive genetic report must include essential patient details such as name, medical record number or birth date, sex, and ethnicity. The report should also specify the type of specimen received, identification number, laboratory test requested, the performing laboratorys name and address, and referring healthcare professional or hospital. The date of the report, analytic result interpretation using standard nomenclature, detailed method description (including literature citations if applicable), and assay sensitivity and specificity should be provided. For example, sensitivity and specificity should be reported regarding the number of variants analyzed, the proportion of variants not detected, and the possibility of genetic heterogeneity and recombination.[55]Reports from clinical DNA laboratories should include a disclaimer due to the prevalence of laboratory-developed tests (LDTs) or procedures (LDPs) designed, developed, and validated internally by each laboratory but remain unapproved by the FDA.[56]

Fluorescent tags binding to chromosomes reveal chromosomal abnormalities in FISH. MLPA detects copy number variations by correlating peak intensity during capillary electrophoresis with sample copy numbers. An MLPA probe's amplification signals the presence of a mutation in the sample.

An MLPA test can yield two outcomes:

DHPLC detects mutations by identifying heteroduplexes compared to the reference genome in the same sample. NGS identifies various genetic variants, including single nucleotides, small insertions or deletions, and some structural variants, but their role in the disease is not implied. Clinical analysis and assessment of the pathological potential of detected variants require consideration in different contexts.[58]Sanger sequencing results interpretation depends on the target DNA strand and primer availability. If strand A is of interest but the primer suits strand B better, the output matches strand A. Conversely, if the primer suits strand A better, the output aligns with strand B, necessitating conversion back to strand A.

FISH probe specificity prevents unintended hybridization with nontarget genes. Some FISH preparations may exhibit autofluorescence, necessitating thorough cell washing to remove fluorescent residues and reduce background fluorescence.

MPLA has limitations, including its ability to detect only known mutations designed into probes, making gene rearrangements like inversions and translocations undetectable. Sample purity is essential as contaminants such as phenol can interfere with the ligation step. MLPA may yield false positive or negative results due to rare sequence variants in target regions detected by probes. Reduced probe binding efficiency from point mutations or polymorphisms candiminishthe relative peak areas height. Confirmation of single exon deletions detected by MLPA is thus recommended using other methods like multiplex PCR or sequencing.[59]

DHPLC sensitivity relies on melting temperature. Computational algorithms can predict the melting temperature, and the procedure typically involves at least 2 melting temperatures for increased sensitivity. CMA does not detect point mutations, small DNA segment changes (eg, in Fragile X syndrome), or balanced chromosomal rearrangements (eg, balanced translocations, inversions).

NGS technologies continue to evolve to address various challenges. Some large sequencers can detect large insertions, duplications, and deletions, while sequencing long homopolymer regions remains problematic. However, establishing the infrastructure and expertise for data analysis remains a significant challenge in clinical settings. The primary limitation of implementing NGS in clinical settings is the requirement for adequate infrastructure, including computational resources, storage capacity, and skilled personnel for comprehensive data analysis and interpretation.

Despite automation, Sanger sequencing remains labor-intensive, time-consuming, and expensive, relying on specialized equipment. Sanger sequencing exhibits reduced sensitivity in detecting point mutations when 20% of mutant DNA is of a wild-type background. Additionally, it lacks quantifiability, making it impossible to differentiate mutation prevalence accurately based solely on peak sizes, necessitating supplementary testing approaches.

Peripheral blood collection via venipuncture infrequently leads to serious complications. Some patients, especially children, may experience hematomas, pain, and fear, which are expected. In contrast, procedures like amniocentesis are more invasive, thus posing more serious risks such as infection, preterm delivery, respiratory distress, trauma, and alloimmunization, though these complications are also infrequent.[60]Genetic tests using NGS of free-cell DNA from maternal peripheral blood offer an alternative to diagnosis using amniocentesis fluid.[61]

Molecular testing may give rise to legal, medical, psychological, and ethical issues besides the sampling procedures potential complications.[62]While molecular testing primarily aims to demonstrate a genetic trait associated with a disease, the current recommendation is to integrate the results into genetic counseling.[63]

Genetic counseling, led by a team including genetic counselors and other professionals, begins with clinically identifying suspected diseases to guide molecular testing. Patients are informed about the testing procedure, potential results, and legal considerations like informed consent, particularly for children.[64]Patient education is integral to this process.

NGS technologies applied to genetic counseling yield complex results surpassing traditional tests, necessitating informed patient discussions due to the considerable information and ethical implications involved.[65]Laboratories conducting molecular genetic tests should address preexamination, examination, and postexamination considerations, tailoring methodology and interpretation to each test's indication, application, and ethical implications.

Any permanent alteration in a gene's nucleotide sequence compared to a reference genome is deemed a genetic change or mutation. Variants identified through a tiered protocol must undergo sequencing confirmation, and their role in disease pathology must be assessed. Genetic testing may reveal variants classified as benign, likely benign, pathogenic, likely pathogenic, or of uncertain significance.[66]Variants must be rigorously classified based on various types of evidencepopulation, computational, functional, or segregation datato determine clinical significance.[67]

The American College of Medical Genetics and Genomics recommends this nomenclature and classification for genetic test findings, covering genotyping, single genes, panels, exomes, and genomes. NGS applications have deepened our understanding of genetic diseases and led to the discovery of variants requiring further study of their disease implications.[68]Interprofessional collaboration is essential for leveraging genetic tests for patient benefit, withan expertpanel advocating for results interpretation by a board-certified geneticist.[69]

Molecular genetic testing advanced significantly with PCR and NGS, providing genome-wide data.[70]Multidisciplinary teams collaborate to integrate various testing methods with clinical, pathological, functional, computational, ethical, and social aspects of diseases for patient benefit.[71]

Polymerase Chain Reaction. This diagram shows the polymerase chain reaction steps. Enzoklop,Public Domain via Wikimedia Commons

Trisomy 21 on G-Banded Chromosome Studies. This karyogram depicts trisomy 21 resulting from an inherited Robertsonian translocation between chromosomes 14 and 21. The infant's father was a carrier of the translocation in a balanced form. Crotwell PL, (more...)

Disclosure: Cecilia Ishida declares no relevant financial relationships with ineligible companies.

Disclosure: Muhammad Zubair declares no relevant financial relationships with ineligible companies.

Disclosure: Vikas Gupta declares no relevant financial relationships with ineligible companies.

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Molecular Genetics Testing - StatPearls - NCBI Bookshelf

Genetics is the study of genes, genetic variation, and heredity in living organisms. This online textbook covers major topics in molecular genetics in a problems-based approach. It grew out of teaching a course for upper level undergraduates and graduate students at the Pennsylvania State University.

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Working with Molecular Genetics (Hardison) - Biology LibreTexts

The complex molecular underpinnings of genetic and rare diseases offer a promising avenue for scientific exploration and innovation. This research topic explores the intricate molecular mechanisms driving these conditions, underlining the latest developments in diagnostic methodologies and therapeutic approaches. Due to the rapid advancement in molecular diagnostics, including Next-Generation Sequencing, our insights into rare and genetic diseases have expanded significantly.

Through this research topic, our aim is to uncover genetic and molecular mechanisms driving the onset and progression of genetic and rare diseases, with a particular focus on unraveling actionable therapeutic targets. By integrating advanced molecular biology methods, including Next-Generation Sequencing, CRISPR, and other cutting-edge technologies, this topic emphasizes the development of novel therapeutic approaches. The goal is to translate these molecular insights into innovative, personalized therapies that address the specific challenges of genetic and rare diseases, ultimately improving patient outcomes and advancing the field of precision medicine.

This Research Topic addresses significant challenges in accurately diagnosing and effectively treating genetic and rare diseases. Despite advances in molecular diagnostics, many of these conditions remain underdiagnosed or misdiagnosed, delaying crucial interventions. Recent developments in technologies like Next-Generation Sequencing have revolutionized our ability to detect genetic anomalies, but there is still a need to bridge the gap between these diagnostics and targeted therapeutic strategies. This topic seeks to explore how integrating advanced molecular tools with therapeutic innovations can lead to more precise and personalized treatments, ultimately improving outcomes for patients with genetic and rare diseases.

We welcome submissions of original research articles, in-depth reviews, case studies, and perspective pieces that advance the understanding of the genetic and molecular foundations of genetic and rare diseases. Contributions that explore novel diagnostic tools, therapeutic strategies, and translational research are particularly encouraged.

This Research Topic will cover a wide range of themes related to genetic and rare diseases, including but not limited to:

Identification and characterization of novel genetic mutations and their clinical implications;

Advances in molecular diagnostic technologies, including Next-Generation Sequencing and multi-omics approaches;

Development of targeted therapies and personalized treatment strategies for rare and genetic disorders;

Translational research bridging molecular diagnostics and therapeutic applications;

Ethical and clinical considerations in the treatment of genetic and rare diseases.

Keywords:Rare Diseases, Genetic Diseases, Next-Generation Sequencing, Molecular Diagnostics, Clinical Genomics

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.

Through this research topic, our aim is to uncover genetic and molecular mechanisms driving the onset and progression of genetic and rare diseases, with a particular focus on unraveling actionable therapeutic targets. By integrating advanced molecular biology methods, including Next-Generation Sequencing, CRISPR, and other cutting-edge technologies, this topic emphasizes the development of novel therapeutic approaches. The goal is to translate these molecular insights into innovative, personalized therapies that address the specific challenges of genetic and rare diseases, ultimately improving patient outcomes and advancing the field of precision medicine.

This Research Topic addresses significant challenges in accurately diagnosing and effectively treating genetic and rare diseases. Despite advances in molecular diagnostics, many of these conditions remain underdiagnosed or misdiagnosed, delaying crucial interventions. Recent developments in technologies like Next-Generation Sequencing have revolutionized our ability to detect genetic anomalies, but there is still a need to bridge the gap between these diagnostics and targeted therapeutic strategies. This topic seeks to explore how integrating advanced molecular tools with therapeutic innovations can lead to more precise and personalized treatments, ultimately improving outcomes for patients with genetic and rare diseases.

We welcome submissions of original research articles, in-depth reviews, case studies, and perspective pieces that advance the understanding of the genetic and molecular foundations of genetic and rare diseases. Contributions that explore novel diagnostic tools, therapeutic strategies, and translational research are particularly encouraged.

This Research Topic will cover a wide range of themes related to genetic and rare diseases, including but not limited to:

Identification and characterization of novel genetic mutations and their clinical implications;

Advances in molecular diagnostic technologies, including Next-Generation Sequencing and multi-omics approaches;

Development of targeted therapies and personalized treatment strategies for rare and genetic disorders;

Translational research bridging molecular diagnostics and therapeutic applications;

Ethical and clinical considerations in the treatment of genetic and rare diseases.

Keywords:Rare Diseases, Genetic Diseases, Next-Generation Sequencing, Molecular Diagnostics, Clinical Genomics

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.

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Molecular Underpinnings of Genetic and Rare Diseases: From ... - Frontiers

The high heritability of schizophrenia has stimulated much work aimed at identifying susceptibility genes using positional genetics. However, difficulties in obtaining clear replicated linkages have led to the skepticism that such approaches would ever be successful. Fortunately, there are now signs of real progress. Several strong and well-established linkages have emerged. Three of the best ...

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The molecular genetics of schizophrenia: New findings promise new insights.

Genetics is the study of the inheritance and variation of biological traits. We have previously noted that it is possible to conduct genetic research without directly studying DNA. Indeed some of the greatest geneticists had no special knowledge of DNA at all, but relied instead on analysis of phenotypes, inheritance patterns, and their ratios in carefully designed crosses.

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8: Techniques of Molecular Genetics - Biology LibreTexts

Genes and Proteins

Since the rediscovery of Mendels work in 1900, the definition of the gene has progressed from an abstract unit of heredity to a tangible molecular entity capable of replication, transcription, translation, and mutation. Genes are composed of DNA and are linearly arranged on chromosomes. Some genes encode structural and regulatory RNAs. There is increasing evidence from research that profiles the transcriptome of cells (the complete set all RNA transcripts present in a cell) that these may be the largest classes of RNAs produced by eukaryotic cells, far outnumbering the protein-encoding messenger RNAs (mRNAs), but the 20,000 protein-encoding genes typically found in animal cells, and the 30,o00 protein-encoding genes typically found in plant cells, nonetheless have huge impacts on cellular functioning.

Protein-encoding genes specify the sequences of amino acids, which are the building blocks of proteins. In turn, proteins are responsible for orchestrating nearly every function of the cell. Both protein-encoding genes and the proteins that are their gene products are absolutely essential to life as we know it.

Replication, Transcription, and Translation are the three main processes used by all cells to maintain their genetic information and to convert the genetic information encoded in DNA into gene products, which are either RNAs or proteins, depending on the gene. In eukaryotic cells, or those cells that have a nucleus, replication and transcription take place within the nucleus while translation takes place outside of the nucleus in cytoplasm. In prokaryotic cells, or those cells that do not have a nucleus, all three processes occur in the cytoplasm.

Replication is the basis for biological inheritance. It copies a cells DNA. The enzyme DNA polymerase copies a single parental double-stranded DNA molecule into two daughter double-stranded DNA molecules. Transcription makes RNA from DNA. The enzyme RNA polymerase creates an RNA molecule that is complementary to a gene-encoding stretch of DNA. Translation makes protein from mRNA. The ribosome generates a polypeptide chain of amino acids using mRNA as a template. The polypeptide chain folds up to become a protein.

The central dogma of molecular biology describes the flow of genetic information in cells from DNA to messenger RNA (mRNA) to protein. It states that genes specify the sequence of mRNA molecules, which in turn specify the sequence of proteins. Because the information stored in DNA is so central to cellular function, the cell keeps the DNA protected and copies it in the form of RNA. An enzyme adds one nucleotide to the mRNA strand for every nucleotide it reads in the DNA strand. The translation of this information to a protein is more complex because three mRNA nucleotides correspond to one amino acid in the polypeptide sequence.

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that enzymes can convert back and forth from DNA to RNA. During transcription, a DNA sequence is read by RNA polymerase, which produces a complementary, antiparallel RNA strand. Unlike DNA replication, transcription results in an RNA complement that substitutes the RNA uracil (U) in all instances where the DNA thymine (T) would have occurred. Transcription is the first step in gene expression. The stretch of DNA transcribed into an RNA molecule is called a transcript. Some transcripts are used as structural or regulatory RNAs, and others encode one or more proteins. If the transcribed gene encodes a protein, the result of transcription is messenger RNA (mRNA), which will then be used to create that protein in the process of translation.

Translation is the process by which mRNA is decoded and translated to produce a polypeptide sequence, otherwise known as a protein. This method of synthesizing proteins is directed by the mRNA and accomplished with the help of a ribosome, a large complex of ribosomal RNAs (rRNAs) and proteins. In translation, a cell decodes the mRNAs genetic message and assembles the brand-new polypeptide chain. Transfer RNA, or tRNA, translates the sequence of codons on the mRNA strand. The main function of tRNA is to transfer a free amino acid from the cytoplasm to a ribosome, where it is attached to the growing polypeptide chain. tRNAs continue to add amino acids to the growing end of the polypeptide chain until they reach a stop codon on the mRNA. The ribosome then releases the completed protein into the cell.

DNA to protein: This interactive shows the process of DNA code being translated to a protein from start to finish!

The genetic code is degenerate as there are 64 possible nucleotide triplets (43), which is far more than the number of amino acids. These nucleotide triplets are called codons; they instruct the addition of a specific amino acid to a polypeptide chain. Sixty-one of the codons encode twenty different amino acids. Most of these amino acids can be encoded by more than one codon. Three of the 64 codons terminate protein synthesis and release the polypeptide from the translation machinery. These triplets are called stop codons. The stop codon UGA is sometimes used to encode a 21st amino acid called selenocysteine (Sec), but only if the mRNA additionally contains a specific sequence of nucleotides called a selenocysteine insertion sequence (SECIS). The stop codon UAG is sometimes used by a few species of microorganisms to encode a 22nd amino acid called pyrrolysine (Pyl). The codon AUG, also has a special function. In addition to specifying the amino acid methionine, it also serves as the start codon to initiate translation. The reading frame for translation is set by the AUG start codon.

The genetic code is universal. With a few exceptions, virtually all species use the same genetic code for protein synthesis. The universal nature of the genetic code is powerful evidence that all of life on Earth shares a common origin.

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1.5: Molecular Genetics - Biology LibreTexts

Abstract

Genetics have undoubtedly become an integral part of biomedical science and clinical practice, with important implications in deciphering disease pathogenesis and progression, identifying diagnostic and prognostic markers, as well as designing better targeted treatments. The exponential growth of our understanding of different genetic concepts is paralleled by a growing list of genetic terminology that can easily intimidate the unfamiliar reader. Rendering genetics incomprehensible to the clinician however, defeats the very essence of genetic research: its utilization for combating disease and improving quality of life. Herein we attempt to correct this notion by presenting the basic genetic concepts along with their usefulness in the cardiology clinic. Bringing genetics closer to the clinician will enable its harmonious incorporation into clinical care, thus not only restoring our perception of its simple and elegant nature, but importantly ensuring the maximal benefit for our patients.

All inheritable traits of living organisms are determined by their genetic material, the genome, a long nucleic acid called deoxyribonucleic acid (DNA). The DNA consists of 3109 nucleotides. Each nucleotide is made up of a sugar (deoxyribose), a nitrogenous base (adenine (A), guanine (G), cytosine (C) or thymine (T)) and a phosphate group () [1,2]. The four nitrogenous bases are divided into two groups: purines (including A and G) have two joined heterocyclinc rings and pyrimides (including C and T) have a single heterocyclic ring. Successive sugar and phosphate residues are linked by covalent phosphodiester bonds, forming the backbone of the DNA molecule and a nitrogenous base is attached to each sugar. The stability of DNA is primarily dependent on the strong covalent bonds that connect the constituent atoms of its linear backbone, and also on a number of weak non-covalent bonds that exist. Meanwhile, because of the phosphate group charges present in each nucleotide, DNA is negatively charged and therefore highly soluble in water.

The chemical structure of a nucleotide including the phosphate (yellow), the sugar (deoxyribose in green) and adenine as the nitrogenous base (pink).

The DNA structure is a double helix, in which two DNA molecules are held together by weak hydrogen bonds [37]. Hydrogen bonding occurs between laterally opposed bases, of the two strands according to Watson-Crick rules: A specifically binds to T, and G to C. The two strands are therefore complementary [8]. As the phosphodiester bonds link carbon atoms number 3 and number 5 of successive sugar residues, the end of each DNA strand will have a terminal sugar residue where carbon atom number 5 is not linked to a neighboring sugar residue, and is therefore called 5 end. The other end of the molecule is similarly called 3 end. The two DNA strands are antiparallel because they always associate (anneal) in such a way that the 53 direction of one DNA strand is the opposite to that of its partner. To describe a DNA sequence, the sequence of bases of one strand only, are usually provided, and are provided in the 53 direction. This is the direction of DNA replication as well as transcription.

The human DNA is estimated to be approximately 2 m long. In order for it to fit in the 10 m nucleus of human cells it is imperative that it is tightly folded. The DNA double helix is therefore subjected to at least two levels of coiling: the first involving coiling around a central core of eight histone proteins, resulting in units called nucleosomes, which are connected by spacer DNA; and the second involving coiling of this string of nucleosomes into a chromatin fiber [3]. During the different phases of the cell cycle, the DNA varies in the extent of its condensation. For example, during interphase the chromatin fibers are organized into long loops, whereas in metaphase chromosomes, the DNA is compacted to about 1/10,000 of its stretched out length. In humans there are 24 different chromosomes, namely 122 autosomes, and sex chromosomes X and Y [9]. Since humans are diploid organisms, our DNA is found in two copies, one inherited from each parent, and is folded into 46 chromosomes. Among the major DNA sequence elements of each chromosome are: the centromeres (constriction site where sister chromatics are joined and chromosomes link to the mitotic spindle), the telomeres (structures capping the ends of chromosomes) and the origins of replication (where DNA replication begins). Chromatin is encountered in extended (euchromatin) or highly condensed (heterochromatin) states, which in turn affect the transcriptional status of the corresponding DNA regions (being active or inactive, respectively) [10]. Under the light microscope, these regions appear as light and dark bands of metaphase chromosomes ().

Diagrammatical representation of the human karyotype of haploid chromosome set with X and Y as the sex chromosome complement. The alternating light and dark bands are characteristic of each chromosome in standard G-banding karyotype, and they represent euchromatic and heterochromatic regions, respectively.

Genomic DNA contains coding as well as non-coding regions. The non-coding regions are involved in DNA folding, chromosome formation, chromatin organization within the nucleus, regulation of transcription and more [1114]. The coding regions are responsible for the transcription of RNA molecules and ultimately protein synthesis.

The genes are stretches of DNA that code for polypeptides. Specifically, genes contain regulatory and coding regions, which regulate their transcription or code for the polypeptide product, respectively. A key regulatory region is the promoter, where the transcription machinery binds for transcription to be initiated. Other possible regulatory regions include enhancers, which regulate gene expression in different tissues or cells, and can be found upstream or downstream of the coding region, as far as several thousand bases. The coding regions are represented by exons, whose size and number varies among different genes. Interspersed between gene exons, there are non-coding sequences named introns, which tend to make up the largest percentage of a gene. The human genome is estimated to contain approximately 20,000 different genes [15]. Interestingly, it is estimated that 80% of the human genome is expressed, yet only 2% is coding for proteins [16].

The central dogma of molecular biology was first stated in 1958 and re-stated in 1970 by Francis Crick [17,18]. According to this dogma there are three major classes of biopolymers: DNA, RNA and protein, and three classes of direct transfer of information that can occur between these biopolymers: general transfers, special transfers and unknown transfers. Of these, only the general transfers are believed to occur normally in most cells and they involve DNA replication to DNA, DNA transcription to mRNA and mRNA translation to proteins ().

The central dogma of molecular biology, as it currently applies in most cells (general transfers = black),or under specific conditions (in some viruses and in vitro: special transfers = grey).

The transfer of information from the DNA to the protein level is achieved step-wise and starts with the transcription of a gene to mRNA. Specifically, the transcription machinery (including RNA polymerase and a variety of transcription factors) binds to the gene promoter, the double helix opens in that location and a single strand primary mRNA molecule (hn-RNA), complementary to that gene sequence, is synthesized base by base () [19]. RNA as opposed to DNA, is a single strand nucleic acid containing ribose instead of deoxyribose and uracil instead of thymine. The heterogenous (hn)-RNA molecules go through a series of processing steps including a 5 cap, a poly-A (50250 adenine molecules and a 70kDa protein) tail at the 3 end and splicing, to remove the intronic sequences () [2023]. Alternative splicing can also occur, which removes certain exons and contributes to the diversity of proteins any single gene can produce [24].

During transcription the transcription machinery (including RNA polymerase and a variety of transcription factors) binds to the gene promoter, the double helix opens in that location and a single strand primary mRNA molecule (hn-RNA),complementary to that gene sequence, is synthesized base by base.

The promoter and enhancer elements of each gene are involved in gene transcription to precursor mRNA (hn-RNA) molecules which are then appropriately processed to give mature mRNA.

The mature mRNA molecules can be translated to proteins [25]. This process takes place in the cytoplasm with the aid of ribosomes, which are complexes of RNAs and proteins called ribonucleoproteins. The ribosomes are divided into two subunits: the smaller subunit binds to the mRNA, while the larger subunit binds to the tRNA which carries the amino acids. When a ribosome finishes reading a mRNA, these two subunits split apart. In particular, ribosomes bind mRNA and read through it as triplet codons, usually starting with an AUG triplet (initiation codon) downstream of the ribosome binding site. For each codon, the ribosome, with the aid of initiation and elongation factors, recruits a complementary tRNA molecule, which in turn carries a specific amino acid. Each codon codes for a specific amino acid as shown in . As the amino acids are linked into the growing peptide chain, they begin folding into the correct conformation. The translation process ends with the stop codons UAA, UGA or UAG. The nascent polypeptide chain is then released from the ribosome as a mature protein [25]. In some cases the new polypeptide chain requires additional processing to make a mature protein. Mature proteins in turn can be subjected to a range of post-translational modifications. Their ultimate roles in cell physiology can be highly variable including cytoarchitecture, enzymatic activity, intracellular signalling, transportation, communication etc.

Genetic variation refers to genetic difference between individuals within or between different populations. This variation is what renders each individual unique in its phenotypic characteristics. Genetic variation occurs on many different scales, ranging from gross alterations in the human karyotype to single nucleotide changes. These variations can be divided in polymorphisms and mutations.

Polymorphisms are defined as variants found in >1% of the general population [26]. Due to their high frequency they are considered unlikely to be causative of genetic disease. They can however, together with other genetic and environmental factors, affect disease predisposition, disease progression or response to treatments (e.g. [27]). Three common types of polymorphisms are the single nucleotide polymorphisms (SNPs), small insertions/deletions (indels) and the large-scale copy number polymorphisms (CNPs or CNVs). SNPs are single base changes that occur on average about every 1000 bases in the genome. Their distribution is not homogenous and they occur more frequently in non-coding regions where there is less selective pressure () [28,29]. Most SNPs are neutral; yet 35% are thought to have a functional role, i.e. affect the phenotype of the individual carrying them. Depending on their effect at the protein level, SNPs can be characterized as synonymous (coding for the same amino acid as the wild type DNA sequence) or non-synonymous (coding for a different amino acid than the wild type DNA sequence) [29]. Indels are small insertions or deletions ranging from 1 to 10,000 bp in length, although the majority involves only a few nucleotides [30,31]. They are considered the second most common form of variation in the human genome following SNPs, with over 3 million short indels listed in public databases. CNVs are variations in the number of copies of DNA regions. They can involve loss of one or both copies of a region of DNA, or the presence of more than two copies of this region. They can arise from DNA deletions, amplifications, inversions or insertions and their size can range from 1 kb (1,000 bases) to several megabases [32]. SNPs, indels and CNVs can either be inherited or arise de novo.

A Single-Nucleotide DNA Polymorphism (SNP) is defined as a single DNA variation detected when a single nucleotide in the genome (or other common sequence) is different between species or paired chromosomes in an individual. In this case there is a substitution of a C (Cytosine) in a T (Tymine) which causes the change of a G (Guanine) in a A (Adenine) in the complementary DNA strand.

Mutations on the other hand, are rare (by some defined as variations with <1% frequency in the general population, although there are many exceptions to this rule) changes in the DNA sequence that can change the resulting protein, impair or inhibit the expression of the gene, or leave both the gene function and protein levels/structure unaffected. Although a variety of definitions have been considered over the years, for most scientists mutation has become synonymous with disease. They can arise during DNA replication or as a result of DNA damage through environmental agents including sunlight, cigarette smoke and radiation. A variety of different types of mutations exist and the terminology used to describe them is based on their effect either on DNA structure, on protein product function, or on the fitness of the individual carrying them.

In terms of DNA structure modification, mutations can be categorized as:

A) point mutations in which a single nucleotide is changed for a different one (). These are divided into missense mutations (meaning that when translated this DNA sequence leads to the incorporation of a different amino acid into the produced protein, with possible implications in the protein function), nonsense mutations (where the new nucleotide changes the sequence so that a stop codon is formed earlier than in the normal sequence and therefore the produced protein is truncated), silent mutations (where the nucleotide change does not affect the amino acid in the corresponding position of the produced protein, and therefore the final protein product remains unaltered), and splice-site mutations (which affects the splice site invariant donor or acceptor dinucleotides (5GT or 3AG).

Different types of mutation and possible conseuquence on protein function:A) missense mutation; B) nonsense mutation; C) deletion; D) inversion.

B) insertions in which one or more nucleotides are inserted in the normal DNA sequence, therefore disrupting it. This can have a moderate or severe effect on the corresponding mutant protein product. For example it can affect the splicing or the reading frame ( frame-shift mutations), therefore leading an incorrect reading of all the downstream nucleotide triplets and consequently their translation to a significantly different and/or truncated amino acid sequence.

C) deletions in which one or more nucleotides are deleted from the normal DNA sequence (). As in the case of insertions this can lead to minor (e.g. single amino acid changes) or major protein defects (e.g. reading frame modifications with implications for the entire downstream amino acid sequence of the mutant protein). When larger chromosomal regions are deleted, multiple genes can be lost and/or previously distant DNA sequences can now be juxtaposed (such juxtapositions can lead, for example, to the production of abnormal proteins containing sequences from different genes that have now been merged or abnormal expression of otherwise normal proteins by deletions affecting their upstream regulatory regions).

D) amplifications leading to multiple copies of chromosomal regions and consequently to an increased number of copies of the genes located within them and increased levels of the corresponding proteins.

E) inversions involving the reversal of the orientation of a DNA segment, with variable implications for the protein product, similar to the ones described above ().

F) translocations where regions from non-homologous chromosomes are interchanged.

Mutations can affect the expression of a transcript and its corresponding protein, or modify the structure of the resulting protein therefore impairing its function [33]. Depending on their functional effect, mutations can be classified as dominant negative (the mutant gene product acts antagonistically to the wild-type allele), gain-of-function (the mutant gene product gains a new and abnormal function), and loss-of-function (the mutant gene product has less or no function). Loss-of-function mutations can be associated with haploinsufficiency, a common occurrence in the molecular cardiomyopathy setting.

Haploinsufficiency occurs when the gene product of one of the two alleles in an individual is lost due to a DNA deletion or to instability/degradation of the mutant protein. Other terms used to describe the effect of a mutation on the fitness of the carrier are: harmful or deleterious mutations (decreases the fitness of the carrier), beneficial or advantageous mutations (increases the fitness of the carrier), and lethal mutations (leading to the death of the individual carrying them).

In the field of cardiovascular genetics, when a new genetic variant is identified a common occurrence given the large number of genes and different variants thereof being screened it is crucial to first determine whether it represents a benign polymorphism or a pathogenic mutation. Identifying pathogenic mutations enables the characterization of the molecular mechanisms of pathogenesis, and more importantly for the clinical setting, it allows the development of genetic tests for mutation detection in other family members (including pre-symptomatically) as well as unrelated patients with similar phenotypes (see section on Cardiovascular genetics in clinical practice).

The Clinical Molecular Genetics Society1 and the American College of Medical Genetics2 have issued guidelines to facilitate the determination of the potential pathogenic role of a novel/unclassified variant (). The Human Gene Mutation Database,3 along with locus-specific or disease-specific mutation databases, are valuable resources for first deciphering whether a detected genetic variant represents a known mutation. The databases Online Mendelian Inheritance in Man,4 dbSNP5 and Ensembl,6 along with thorough searches of the literature via PubMED, Google Scholar, Scopus or the Web of Science, can also provide valuable information. From thereon carefully matched controls need to be included in the study populations, co-occurrence with known (in trans) deleterious mutations in the same gene needs to be ruled out, co-segregation with the disease in the family represents useful information, and occurrence of the novel variant concurrent with the incidence of a sporadic disease can be a strong indicator. Bioinformatically, it is important to determine if the unclassified variant leads to an animo acid change and how different the biophysical properties of the new amino acid are: the greater the difference, the higher the likelihood to possess a pathogenic role. Similarly, the more conserved a DNA region is across species, the greater an impact any variations therein are likely to have. A range of in silico analysis tools can also be used for the predication of a pathogenic effect (e.g. Align GVGD, Sorting Intolerant From Tolerant [SIFT], Polyphen, and Alamut) or the prediction of splice sites. One of the best means of determining pathogenicity, however, is the use of suitable functional assays and transgenic animal models [34,35].

From mutation to disease. A DNA mutation can cause qualitative or quantitative changes at the protein level, leading to either a dysfunctional/non-functional protein product and/or aberrant protein expression levels. Both mechanisms can in turn lead to CVD.

Once a mutation has been directly associated with a pathological phenotype a number of additional parameters need to be evaluated in order to maximize its value in the clinical setting. These parameters relate to the mode of inheritance of a mutation, which impacts directly the chances of detecting it in other family members of the patient, or his/her offspring. The categorization gonosomal or autosomal depends on whether the mutations are located on either of the sex chromosomes or not. For example a mutation on the Y chromosome will only affect males. The dominant or recessive nature relates to the need of one or both alleles, respectively, to carry the mutation for the pathogenic phenotype to develop. In hypertrophic cardiomyopathy (HCM) a number of cases have been reported with homozygosity for the pathogenic mutation. Nishi et al. first reported homozygosity for a MYH7 mutation in two brothers with HCM [36]. Homozygous mutations were also detected in MyBPC in HCM patients [37]. The patients who harbour homozygous mutations present with a more severe clinical phenotype than their heterozygous family members. These observations support the notion of a mutation dosage effect, in which a larger amount of the defective protein leads to a greater disruption of the sarcomere function and results in a more severe clinical outcome. For example, in our Egyptian HCM cohort, none of the mutation-positive patients were homozygous for the mutation detected (data not published) which might be explained either by the rarity of its occurrence in the specific cohort or due to technical limitations in the mutation screening method ().

Mutation screening by denaturing high performance liquid chromatography (dHPLC) using WAVE, Transgenomics. dHPLC can be used as an initial mutation screening method, being dependent on heteroduplex (wild type-mutant) formation, and variant profiles from the wild pattern are subsequently sequenced. Note however, that dHPLC is not capable of detecting homozygosity.

Importantly, a number of exceptions apply to the aforementioned inheritance mode rules, such as in the case of incomplete penetrance (a percentage of the individuals carrying the mutation fail to present the corresponding trait) where mutation carriers may not present with any symptoms even in the presence of a dominant mutation. Furthermore, the phenomena of variable expressivity (variations in a phenotype among individuals carrying a particular genotype) and epistasis (one gene is modified by one or several other genes, e.g. modifier genes) can lead to a range of pathological characteristics despite the presence of the same mutation. These parameters, potentially in combination with environmental factors, can often lead to significant clinical heterogeneity in most inherited CVDs, between unrelated individuals as well as family members carrying the same mutation () [38].

Role of genetic and environmental factors in determining the spectrum of the disease phenotype.(Strachan T, Read AP. Genes in pedigrees and populations in Human molecular genetics 3. 3rd ed. London; New York: Garland Press; 2004).

Another exception is this of compound heterozygotes (carriers of two different mutations on the two alleles of the same gene) or double heterozygotes (carriers of mutations in two different genes), which carry one copy of each mutation, yet they can develop the disease. Notably, the concomitant presence of multiple genetic defects contributing to the same disease is usually associated with a more severe clinical phenotype. For example, in HCM the presence of multiple pathogenic mutations could be included amongst the risk stratification criteria [39]. Multiple mutations have been observed in about 5% of HCM patients and they are usually associated with higher septal thickness and worse clinical outcomes, such as heart failure and sudden death [4043]. Double heterozygosity is commonly detected in the Myosin heavy chain (MYH7) and Myosin binding protein C (MyBPC) genes, probably because they represent the most commonly involved genes in the pathogenesis of HCM. Compound heterozygosity in MyBPC however, leading to the absence of a normal protein, has been reported to results in neonatal death in two independent cases, where the parents were each heterozygous for one of the mutations [44]. Similarly to HCM, double heterozygosity has been reported in other CVDs such as long QT, with a similar frequency of 5% [45].

Hereditary CVDs include a variety of different aspects and structures of the cardiovascular system such as inherited cardiomyopathies, arrhythmias, metabolic disorders affecting the heart, congenital heart diseases, as well as vascular disorders such as Marfan syndrome [4648]. Over the past two decades significant progress has been made towards the identification of the genetic basis of CVD, with tens of genes now known to be implicated in almost all of the different disorders. The magnitude of the role of genetics however, remains elusive. Although in some cases the pathogenesis appears to involve complex mechanisms and multifactorial (genetic and environmental) aetiology, multigenic inheritance (e.g. familial hypercholesterolemia: LDLR, APOB, ABCG5, ABCG8, ARH, PCSK9; hypertrophic cardiomyopathy: MYH7, TNNT2, TPM1, TNNI3, MYL2, MYBPC3, ACTC, MYL3) or even monogenic, also known as Mendelian, inheritance (e.g. Marfan syndrome: FNB1) has been described. Pinpointing the gene(s) and their specific mutations that lead to each pathological phenotype can give rise to valuable, complementary genetic diagnostic/prognostic tools for significantly improved clinical management of CVD patients and their families.

For example, the recently published consensus statement on the state of genetic testing for cardiomyopathies and channelopathies has elegantly presented the list of different genes which contribute by >5% to these inherited disorders. [49,50]. There are more than 50 distinct channelopathy/cardiomyopathy-associated genes with hundreds of mutations discovered to date. Each of these mutations/genes usually accounts for a small percentage of the reported cases, while in many cases the causative mutation/gene is never identified. For example, in channelopathies a mutation is found in <20% of short QT syndrome cases and up to 75% in long QT syndrome cases. An exceptional scenario is this of mutations in the cardiac ryanodine receptor (RYR2) gene in catecholaminergic polymorphic ventricular tachychardia, which account for up to 65% of affected patients [51]. In cardiomyopathies, positive genetic testing results range in frequency from <20% in restrictive cardiomyopathy to 60% in familial HCM. Despite the fact that two decades ago, HCM was termed a disease of the sarcomere involving at least 8 causative genes, the rate of mutation detection ranged in frequency from 2530% in MyBPC and MYH7 to 5% in TNNT2 and TNNTI3, and 1% in other sarcomeric genes [42,52]. Additionally, there are HCM phenocopies (same phenotype) associated with non-sarcomeric gene mutations and different modes of inheritance, which may on occasion be difficult to exclude from sarcomeric HCM based on clinical evaluation alone. Therefore, multiple genes need to be screened for a multigenic disease such as HCM.

Overall, our understanding of the genetic basis of CVD has been rapidly expanding over the years with important lessons learned both on monogenic as well as complex disease forms [53]. However, the true value of these findings lies in their translation to the clinical setting and their utilisation towards improved CVD diagnosis, prognosis and treatment. Along these lines, genetic testing is currently available for a number of CVDs in the form of clinical service in most Western countries, and increasingly in the developing world.

Genetic testing can serve three main goals in the clinical practice: first to determine the mode of inheritance of the specific disease in the specific family and identify if there is risk for other family members; second to organize the clinical assessment of unaffected family members through predictive genetic testing so as to distinguish those who are at risk for the disease and should have regular cardiac follow-up (mutation carriers) and those who are not (mutation non-carriers); third, following the establishment of distinct genotypephenotype correlations, the application of genetic testing in disease diagnosis, prognosis and personalized treatment (i.e. identification of the drugs to which each patient will respond best) [54].

The clinical value of genetic screening of a cardiovascular disease patient is therefore valuable initially at the diagnostic/prognostic/therapeutic level, provided the genotypephenotype associations have been established first. These associations vary considerably among different cardiovascular diseases, different genes and different mutations thereof. The relevance of genetic testing towards these three levels of clinical management is possibly best shown in the setting of the long QT syndrome [49,50]. It is critical to note however, that genetic testing in the cardiovascular disease setting cannot be the basis for clinical management of patients, but can serve a complementary role to the comprehensive clinical evaluation to better address the patient's and his/her family's needs.

Identifying the causative mutation of a proband further allows the genetic screening of its family members, a process of marked predictive power and therefore high importance in the cardiovascular clinic [55]. The significance of such pre-symptomatic genetic testing for the probands family members ranges from ensuring that unaffected mutation carriers receive regular clinical follow-up and prophylactic treatment (where available) to reassurance that clinically suspicious findings are unlikely to be indicative of the specific form of the disease in the absence of the specific family mutation (e.g. ) [56,57]. Importantly however, a negative genetic test result in the proband's family members cannot by itself exclude the presence of disease in general, since a large number of different genes and a variety of mutations thereof can contribute to the same or a different pathological cardiovascular phenotype and by chance, a family member could be a carrier of a different gene mutation.

Pedigree of an HCM positive family from the BA HCM Study. A pathogenic mutation in MYH7 exon 23 (Glu927Lys) was detected in the proband II-4. Echo screening of all siblings was undertaken, and sister II-10 was found to have an interventricular septal measurement of 14 mm. Genetic screening of all family members excluded HCM diagnosis for the sister (II-10).However, the symptom free and echo clear son of the proband, was positive for the mutation and therefore given a pre-symptomatic diagnosis of HCM at the age of12 years. Symbols in white represent unaffected individuals, in black are individuals with HCM based on clinical or genetic findings, and in blue are individuals who have not been screened by echo or genetic testing (unpublished data).

Genetic testing of children in the family has always posed an ethical concern, particularly for adult-onset diseases. Therefore pre-symptomatic testing of children should be extensively discussed with the family after a mutation has been identified in the proband, and in the context of the specific cardiovascular disease [58]. In cases where pre-symptomatic genetic screening and mutation identification has direct implications on the child's clinical follow-up, lifestyle adaptations and preventive treatments, it would be valuable to proceed with genetic testing, upon the parents approval. For example, for long QT syndrome and catecholaminergic polymorphic ventricular tachychardia, and occasionally in high risk HCM families, in which preventive measures or prophylactic therapy is advisable for asymptomatic mutation positive family members, genetic testing should be undertaken in early childhood, i.e. regardless of age. On the other hand, for late-onset and/or reduced penetrance diseases, it is reasonable to proceed with clinical monitoring as needed during childhood, leaving the genetic testing option open for when the individual reaches adulthood [49,50]. When a child has already presented with a CVD, the use of genetic testing is complementary to all other clinical tests, and especially valuable for identifying other family members at risk, since childhood-onset cases, even when presumed as sporadic, can often have a genetic aetiology. For example, approximately half of the presumed sporadic cases of childhood-onset hypertrophy have genetic causes [59].

Although the translation of molecular genetics to routine clinical practice is slow, a series of certified genetic testing centers (www.genetests.org) have been established, and guidelines have already been issued for a number of cardiovascular diseases such as HCM, dilated cardiomyopathy (DCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC) [60,61]. The consensus is that a minimum of three to four generation family history needs to be obtained, the relatives at risk need to be identified and directed for clinical screening, the potential genetic nature of the disease needs to be explained, and the possibility of genetic testing should be discussed where appropriate.

In order to follow these guidelines, cardiology clinics around the world need to ensure that cardiologists are provided with appropriate training in key genetic concepts, along with information on the latest developments in cardiovascular genetics and the best means to apply them in the clinic. Importantly, the close interaction between cardiologists, geneticists and genetic counsellors, especially in complex cases, will significantly expedite the benchside-to-bedside translation of the latest genetic discoveries and optimize the clinical care provided to the patient [62,63]. For example, when routine cardiovascular genetic screening fails to detect the causative mutations, screening can be extended to include broad gene panels and/or application of high throughput technologies. Similarly, in cases where new mutations are identified, targeted genetic tests can be designed, if needed, for screening family members at risk. Currently, different modes of cardiologist-geneticist interactions are being adopted in clinical settings around the world, a process that requires time, continuing education and to some extent, reorganization of health systems [64]. An example of such an evolving system of interdisciplinary interactions is that of the Egyptian National Genetic study of HCM ().

Combined clinical and genetic evaluation of CVD patients will allow for improved disease management and patient care.

In conclusion, cardiovascular genetic testing is valuable for improving the standards of care for CVD patients and their families at the diagnostic, prognostic and therapeutic level. Importantly, for healthcare systems worldwide, it further represents a cost-effective approach by enabling the timely identification of individuals at risk, ensuring regular follow-up only for the individuals at risk and early disease detection, as well as enabling, where possible, the use of disease preventative measures in order to minimize the environmental contributing factors [65]. To this end, clinical cardiovascular genetics is increasingly emphasized in undergraduate and postgraduate medical education and incorporated in cardiological clinics worldwide [54].

The tremendous technological advancements over the past decade have empowered the discovery of new biological concepts and the emergence of entirely new scientific fields. Among them, cardiac systems genetics a systems-based analysis of genetic variants considering all different levels spanning from their effect on the cardiac transcriptome, proteome, metabolome to organ physiology/pathophysiology (phenome) (). The global analysis of the downstream functional molecular and cellular implications of different genetic variants, will allow the meaningful integration of molecular and clinical data in a powerful way.

To fully unravel the intricate pathways regulating cardiac physiology and pathophysiology the global studies of the human genome will need to be extended to similar studies at the epigenome (chemical changes to the DNA and histone affecting the chromatin structure and function of the genome),transcriptome (the full set of transcripts produced from the human DNA), miRNome (the full set of microRNAs produced from the human DNA), proteome (the full set of proteins) and metabolome (full set of metabolites) levels.

Systems genetics will in turn, serve as an integral part of network medicine, an advanced form of molecular medicine, where perturbations, rather than individual molecules, are investigated as the underlying causes of complex diseases [66]. In cardiology, examples of important first steps in this direction are the identification of cardiac gene expression signatures related with response to left ventricular assist device implantation [67,68] and peripheral leukocyte expression signatures indicative of post-cardiac transplantation tissue rejection [69]. Parameters such as epigenetics and microRNAs are increasingly integrated in network medicine, adding new dimensions to the intricate mechanisms of cardiovascular disease (e.g. [70,71]). A likely next addition to network medicine, based on emerging new data [72,73], could be this of metagenomics the genomic investigation of micro-organisms inside the human body, and their effect on the global networks orchestrating human cardiac physiology/pathophysiology.

Cardiology is rapidly transformed with powerful new technologies expediting the acquisition of new knowledge and exciting new discoveries enriching our understanding of the intricate genotypephenotype correlations. The close interaction of cardiologists and geneticists is facilitating the transition of novel findings to clinical practice and vice versa. It is also enabling the rapid establishment of appropriate research strategies to address emerging clinical questions. Ultimately the convergence of the two disciplines promises to transform the way we perceive, manage and treat CVD.

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Molecular genetics made simple - PMC - National Center for ...

Figure 1: Dolly the sheep was the first cloned mammal.

The three letters DNA have now become associated with crime solving, paternity testing, human identification, and genetic testing. DNA can be retrieved from hair, blood, or saliva. With the exception of identical twins, each persons DNA is unique and it is possible to detect differences between human beings on the basis of their unique DNA sequence.

DNA analysis has many practical applications beyond forensics and paternity testing. DNA testing is used for tracing genealogy and identifying pathogens. In the medical field, DNA is used in diagnostics, new vaccine development, and cancer therapy. It is now possible to determine predisposition to many diseases by analyzing genes.

DNA is the genetic material passed from parent to offspring for all life on Earth. The technology of molecular genetics developed in the last half century has enabled us to see deep into the history of life to deduce the relationships between living things in ways never thought possible. It also allows us to understand the workings of evolution in populations of organisms. Over a thousand species have had their entire genome sequenced, and there have been thousands of individual human genome sequences completed. These sequences will allow us to understand human disease and the relationship of humans to the rest of the tree of life. Finally, molecular genetics techniques have revolutionized plant and animal breeding for human agricultural needs. All of these advances in biotechnology depended on basic research leading to the discovery of the structure of DNA in 1953, and the research since then has uncovered the details of DNA replication and the complex process leading to the expression of DNA in the form of proteins in the cell.

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4 Introduction to Molecular Genetics - University of Minnesota Twin Cities

DefinitionnounA branch of genetics that deal with the structure and function of genes at a molecular levelSupplementGenetics is a basically a study in heredity, particularly the mechanisms of hereditary transmission, and the variation of inherited characteristics among similar or related organisms. Some of the branches of genetics include behavioural genetics, classical genetics, cytogenetics, molecular genetics, developmental genetics, and population genetics.Molecular genetics, in particular, is a study of heredity and variation at the molecular level. It is focused on the flow and regulation of genetic information between DNA, RNA, and proteins. Its sub-fields are genomics (i.e. the study of all the nucleotide sequences, including structural genes, regulatory sequences, and noncoding DNA segments, in the chromosomes of an organism) and proteomics (i.e. the study of proteins from DNA replication). The different techniques employed in molecular genetics include amplification, polymerase chain reaction, DNA cloning, DNA isolation, mRNA isolation, and so on. Molecular genetics is essential in understanding and treating genetic disorders. It is regarded as the most advanced field of genetics. The Human Genome Project was a large scientific research endeavor in molecular genetics. It began in 1990s and finished in 2003 with the intent of identifying the genes and the sequences of chemical base pairs in human DNA.See also:

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Molecular genetics - Definition and Examples - Biology Online

Genetics has become one of the most diverse branches of science as it deals with heredity, inheritance, and how certain traits are expressed.

Molecular genetics focuses more on the molecules at work in geneticsspecifically DNA, RNA, and the proteins responsible for expressing traits.

This branch of genetics is instrumental in diagnosing genetic disorders. With molecular genetics, scientists and doctors can pinpoint abnormalities or changes within gene sequences.

The study of human DNA has propelled modern medicine towards actionable solutions for even the most difficult genetic conditions and mutations. By observing the molecular structure of DNA, geneticists can determine any deviation and mutation that may cause trouble down the road.

Molecular genetics is concerned with what makes DNAthat is, the molecules that are at work.1 Its a biomedical science concerned with human genes and the genetic material DNA consists of, as well as their nucleotide sequences and structures at the molecular level.

It is also considered the marriage of genetics and molecular biology, the study of the building blocks of every object.

This science shows us how genes inside our DNA determine everything from eye color to disease risk.

Geneticists, scientists, and medical professionals can determine how genes work and how any divergence from the norm can contribute to genetic disorders and abnormalities by exploring the special processes and properties of DNA molecules and their molecular mechanisms.

Molecular genetics breaks down into smaller fields, including:

Don't miss out on the opportunity to learn more about yourself. Read our best DNA test page to find the best one for you.

Yes. Molecular genetics falls under genetics.

Genetics is a broader branch of biology that deals with anything related to genes, traits, and inheritance. Its the study of how genes are passed down from parents to offspring through DNA sequences.2

19th-century monk Gregor Mendels famed pea plant experiments laid the foundation for modern genetics. Since then, niche branches of genetics have become specializations, such as:

DNA, or deoxyribonucleic acid, has a double helix structure thats made up of chemical components called nucleotides.3

Nucleotides, which form the DNA ladder, have three important parts:

The entirety of an organisms set of DNA or genetic material is called a genome. Each genome has all the instructions necessary for an organism to develop.

Every cell in that organism will have the same genome so that when they replicate themselves, they all still contain the exact same instructions.

Molecular genetic testing is when a DNA segment or a gene sequence is inspected for any mutations.4 A DNA strand is often looked closely at and analyzed to determine any variations at the molecular level.

Its compared to normal genetic material and any deviations or mutations are taken note of. Any variance in a gene is then explored.

Different mutations can lead to different genetic conditions. For example, a copy of a chromosome can lead to specific genetic disorders, depending on which chromosome has been duplicated.

Other conditions can also arise from the complex interplay of multiple genetic variants. So a thorough study of the DNA sequence is necessary to determine potential congenital risks.

A DNA molecule can also be further looked at to see how its structure contributes to the persons traits.

Genetic tests can be a little pricey, but its well worth the price tag when you consider what they can tell you.

Molecular genetics is being used today all over the world. Its especially used in a lot of genetic research and genetic testing.

When you get a genetic test done to find out more about your ancestry and heritage, you are investing in molecular genetics.

Your DNA sequence may exhibit similarities with the sequences of people who originate from a certain region. If you share certain key similarities, its a good indicator that you or your ancestors may also be from that area.

This helps you unlock more of your past and potentially provide you with closure around your past. Who knows, you may even find out you have royal ancestry.

If your parents had a genetic test done on you when they were pregnant with you to determine if you were at risk for any genetic disease, molecular genetics provided the results.

Geneticists and genetic counselors who tap into family history and rely on testing delve into your molecular structure and practice molecular genetics to give you better insight into your health. Many human diseases can be traced in family medical history via molecular genetics.

You can also determine if any diseases run in your family and what you can do to prevent contracting them.

In biological sciences, molecular genetics helps us understand the molecular basis of living things. It reveals the why behind how our bodies work at the very smallest level.

The biology of genes has helped us understand why certain genes are expressed over others, how we inherit traits, and the way our alleles work together.

Through the biological lens of genetics, weve been able to develop more medicine, apply more agricultural uses, and even explore gene editing.

Molecular genetics has made strides in forensics, given that its allowed us to identify DNA matches via fingerprints or other potential DNA samples.

Its also a huge help in the courtroom, as legal systems often use DNA testing to prove paternity or exonerate crimes.

Looking for a DNA test that's accurate and can tell you about your health and heritage?

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A Detailed Look at the Science of Molecular Genetics - KnowYourDNA

Research Interests

Mendelian principles have been the cornerstone for identifying nuclear genes in biological and diseases processes and ordering these genes into functional cascades. However, the limitation of Mendelian genetics to explain many complex traits has redirected attention beyond the nucleus. In addition to the nuclear genome, each eukaryotic cell contains hundreds to thousands of copies of mitochondrial genome, the small circular DNAs inside mitochondria. Mutations on mitochondrial genome often impair cellular energy homeostasis and have been linked to many diseases including various age-related disorders. Despite the immense impact of mtDNA mutations on health and disease, our understanding of mitochondrial genetics remains rudimentary. Genetic analyses on mitochondrial genome are complicated by the peculiarities of the mitochondrial genetic system that features maternal inheritance, polyploidy, and amitotic segregation.

We are working with fruit flies and other model organisms to understand the basic principles guiding the transmission of mitochondrial genome. We are trying to understand why evolution favors the transmission of mitochondrial genome from the maternal linage exclusively, how mothers limit the transmission of harmful mtDNA variants to their offsring, how organisms prevent the accumulation of mtDNA mutations in somatic tissues and with aging. We are also exploring the coordination and potential genetic conflicts between nuclear and mitochondrial genome, and their impact on health and diseases. Additionally, we are actively developing new tools to advance the genetic study of mtDNA.

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Molecular Genetics | NHLBI, NIH

Branch of biology that studies biological systems at the molecular level

Molecular biology is a branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions.[1][2][3]

Though cells and other microscopic structures had been observed in living organisms as early as the 18th century, a detailed understanding of the mechanisms and interactions governing their behavior did not emerge until the 20th century, when technologies used in physics and chemistry had advanced sufficiently to permit their application in the biological sciences. The term 'molecular biology' was first used in 1945 by the English physicist William Astbury, who described it as an approach focused on discerning the underpinnings of biological phenomenai.e. uncovering the physical and chemical structures and properties of biological molecules, as well as their interactions with other molecules and how these interactions explain observations of so-called classical biology, which instead studies biological processes at larger scales and higher levels of organization.[4] In 1953, Francis Crick, James Watson, Rosalind Franklin, and their colleagues at the Medical Research Council Unit, Cavendish Laboratory, were the first to describe the double helix model for the chemical structure of deoxyribonucleic acid (DNA), which is often considered a landmark event for the nascent field because it provided a physico-chemical basis by which to understand the previously nebulous idea of nucleic acids as the primary substance of biological inheritance. They proposed this structure based on previous research done by Franklin, which was conveyed to them by Maurice Wilkins and Max Perutz.[5] Their work led to the discovery of DNA in other microorganisms, plants, and animals.[6]

The field of molecular biology includes techniques which enable scientists to learn about molecular processes.[7] These techniques are used to efficiently target new drugs, diagnose disease, and better understand cell physiology.[8] Some clinical research and medical therapies arising from molecular biology are covered under gene therapy, whereas the use of molecular biology or molecular cell biology in medicine is now referred to as molecular medicine.

Molecular biology sits at the intersection of biochemistry and genetics; as these scientific disciplines emerged and evolved in the 20th century, it became clear that they both sought to determine the molecular mechanisms which underlie vital cellular functions.[9][10] Advances in molecular biology have been closely related to the development of new technologies and their optimization.[11] Molecular biology has been elucidated by the work of many scientists, and thus the history of the field depends on an understanding of these scientists and their experiments.[citation needed]

The field of genetics arose from attempts to understand the set of rules underlying reproduction and heredity, and the nature of the hypothetical units of heredity known as genes. Gregor Mendel pioneered this work in 1866, when he first described the laws of inheritance he observed in his studies of mating crosses in pea plants.[12] One such law of genetic inheritance is the law of segregation, which states that diploid individuals with two alleles for a particular gene will pass one of these alleles to their offspring.[13] Because of his critical work, the study of genetic inheritance is commonly referred to as Mendelian genetics.[14]

A major milestone in molecular biology was the discovery of the structure of DNA. This work began in 1869 by Friedrich Miescher, a Swiss biochemist who first proposed a structure called nuclein, which we now know to be (deoxyribonucleic acid), or DNA.[15] He discovered this unique substance by studying the components of pus-filled bandages, and noting the unique properties of the "phosphorus-containing substances".[16] Another notable contributor to the DNA model was Phoebus Levene, who proposed the "polynucleotide model" of DNA in 1919 as a result of his biochemical experiments on yeast.[17] In 1950, Erwin Chargaff expanded on the work of Levene and elucidated a few critical properties of nucleic acids: first, the sequence of nucleic acids varies across species.[18] Second, the total concentration of purines (adenine and guanine) is always equal to the total concentration of pyrimidines (cysteine and thymine).[15] This is now known as Chargaff's rule. In 1953, James Watson and Francis Crick published the double helical structure of DNA,[19] based on the X-ray crystallography work done by Rosalind Franklin which was conveyed to them by Maurice Wilkins and Max Perutz.[5] Watson and Crick described the structure of DNA and conjectured about the implications of this unique structure for possible mechanisms of DNA replication.[19] Watson and Crick were awarded the Nobel Prize in Physiology or Medicine in 1962, along with Wilkins, for proposing a model of the structure of DNA.[6]

In 1961, it was demonstrated that when a gene encodes a protein, three sequential bases of a gene's DNA specify each successive amino acid of the protein.[20] Thus the genetic code is a triplet code, where each triplet (called a codon) specifies a particular amino acid. Furthermore, it was shown that the codons do not overlap with each other in the DNA sequence encoding a protein, and that each sequence is read from a fixed starting point.During 19621964, through the use of conditional lethal mutants of a bacterial virus,[21] fundamental advances were made in our understanding of the functions and interactions of the proteins employed in the machinery of DNA replication, DNA repair, DNA recombination, and in the assembly of molecular structures.[22]

In 1928, Frederick Griffith, encountered a virulence property in pneumococcus bacteria, which was killing lab rats. According to Mendel, prevalent at that time, gene transfer could occur only from parent to daughter cells. Griffith advanced another theory, stating that gene transfer occurring in member of same generation is known as horizontal gene transfer (HGT). This phenomenon is now referred to as genetic transformation.[23]

Griffith's experiment addressed the pneumococcus bacteria, which had two different strains, one virulent and smooth and one avirulent and rough. The smooth strain had glistering appearance owing to the presence of a type of specific polysaccharide a polymer of glucose and glucuronic acid capsule. Due to this polysaccharide layer of bacteria, a host's immune system cannot recognize the bacteria and it kills the host. The other, avirulent, rough strain lacks this polysaccharide capsule and has a dull, rough appearance.[citation needed]

Presence or absence of capsule in the strain, is known to be genetically determined. Smooth and rough strains occur in several different type such as S-I, S-II, S-III, etc. and R-I, R-II, R-III, etc. respectively. All this subtypes of S and R bacteria differ with each other in antigen type they produce.[6]

The AveryMacLeodMcCarty experiment was a landmark study conducted in 1944 that demonstrated that DNA, not protein as previously thought, carries genetic information in bacteria. Oswald Avery, Colin Munro MacLeod, and Maclyn McCarty used an extract from a strain of pneumococcus that could cause pneumonia in mice. They showed that genetic transformation in the bacteria could be accomplished by injecting them with purified DNA from the extract. They discovered that when they digested the DNA in the extract with DNase, transformation of harmless bacteria into virulent ones was lost. This provided strong evidence that DNA was the genetic material, challenging the prevailing belief that proteins were responsible. It laid the basis for the subsequent discovery of its structure by Watson and Crick.

Confirmation that DNA is the genetic material which is cause of infection came from the HersheyChase experiment. They used E.coli and bacteriophage for the experiment. This experiment is also known as blender experiment, as kitchen blender was used as a major piece of apparatus. Alfred Hershey and Martha Chase demonstrated that the DNA injected by a phage particle into a bacterium contains all information required to synthesize progeny phage particles. They used radioactivity to tag the bacteriophage's protein coat with radioactive sulphur and DNA with radioactive phosphorus, into two different test tubes respectively. After mixing bacteriophage and E.coli into the test tube, the incubation period starts in which phage transforms the genetic material in the E.coli cells. Then the mixture is blended or agitated, which separates the phage from E.coli cells. The whole mixture is centrifuged and the pellet which contains E.coli cells was checked and the supernatant was discarded. The E.coli cells showed radioactive phosphorus, which indicated that the transformed material was DNA not the protein coat.

The transformed DNA gets attached to the DNA of E.coli and radioactivity is only seen onto the bacteriophage's DNA. This mutated DNA can be passed to the next generation and the theory of Transduction came into existence. Transduction is a process in which the bacterial DNA carry the fragment of bacteriophages and pass it on the next generation. This is also a type of horizontal gene transfer.[6]

The Meselson-Stahl experiment was a landmark experiment in molecular biology that provided evidence for the semiconservative replication of DNA. Conducted in 1958 by Matthew Meselson and Franklin Stahl, the experiment involved growing E. coli bacteria in a medium containing heavy isotope of nitrogen (15N) for several generations. This caused all the newly synthesized bacterial DNA to be incorporated with the heavy isotope.

After allowing the bacteria to replicate in a medium containing normal nitrogen (14N), samples were taken at various time points. These samples were then subjected to centrifugation in a density gradient, which separated the DNA molecules based on their density.

The results showed that after one generation of replication in the 14N medium, the DNA formed a band of intermediate density between that of pure 15N DNA and pure 14N DNA. This supported the semiconservative DNA replication proposed by Watson and Crick, where each strand of the parental DNA molecule serves as a template for the synthesis of a new complementary strand, resulting in two daughter DNA molecules, each consisting of one parental and one newly synthesized strand.

The Meselson-Stahl experiment provided compelling evidence for the semiconservative replication of DNA, which is fundamental to the understanding of genetics and molecular biology.

In the early 2020s, molecular biology entered a golden age defined by both vertical and horizontal technical development. Vertically, novel technologies are allowing for real-time monitoring of biological processes at the atomic level.[24] Molecular biologists today have access to increasingly affordable sequencing data at increasingly higher depths, facilitating the development of novel genetic manipulation methods in new non-model organisms. Likewise, synthetic molecular biologists will drive the industrial production of small and macro molecules through the introduction of exogenous metabolic pathways in various prokaryotic and eukaryotic cell lines.[25]

Horizontally, sequencing data is becoming more affordable and used in many different scientific fields. This will drive the development of industries in developing nations and increase accessibility to individual researchers. Likewise, CRISPR-Cas9 gene editing experiments can now be conceived and implemented by individuals for under $10,000 in novel organisms, which will drive the development of industrial and medical applications.[26]

The following list describes a viewpoint on the interdisciplinary relationships between molecular biology and other related fields.[27]

While researchers practice techniques specific to molecular biology, it is common to combine these with methods from genetics and biochemistry. Much of molecular biology is quantitative, and recently a significant amount of work has been done using computer science techniques such as bioinformatics and computational biology. Molecular genetics, the study of gene structure and function, has been among the most prominent sub-fields of molecular biology since the early 2000s. Other branches of biology are informed by molecular biology, by either directly studying the interactions of molecules in their own right such as in cell biology and developmental biology, or indirectly, where molecular techniques are used to infer historical attributes of populations or species, as in fields in evolutionary biology such as population genetics and phylogenetics. There is also a long tradition of studying biomolecules "from the ground up", or molecularly, in biophysics.[30]

Molecular cloning is used to isolate and then transfer a DNA sequence of interest into a plasmid vector.[31] This recombinant DNA technology was first developed in the 1960s.[32] In this technique, a DNA sequence coding for a protein of interest is cloned using polymerase chain reaction (PCR), and/or restriction enzymes, into a plasmid (expression vector). The plasmid vector usually has at least 3 distinctive features: an origin of replication, a multiple cloning site (MCS), and a selective marker (usually antibiotic resistance). Additionally, upstream of the MCS are the promoter regions and the transcription start site, which regulate the expression of cloned gene.

This plasmid can be inserted into either bacterial or animal cells. Introducing DNA into bacterial cells can be done by transformation via uptake of naked DNA, conjugation via cell-cell contact or by transduction via viral vector. Introducing DNA into eukaryotic cells, such as animal cells, by physical or chemical means is called transfection. Several different transfection techniques are available, such as calcium phosphate transfection, electroporation, microinjection and liposome transfection. The plasmid may be integrated into the genome, resulting in a stable transfection, or may remain independent of the genome and expressed temporarily, called a transient transfection.[33][34]

DNA coding for a protein of interest is now inside a cell, and the protein can now be expressed. A variety of systems, such as inducible promoters and specific cell-signaling factors, are available to help express the protein of interest at high levels. Large quantities of a protein can then be extracted from the bacterial or eukaryotic cell. The protein can be tested for enzymatic activity under a variety of situations, the protein may be crystallized so its tertiary structure can be studied, or, in the pharmaceutical industry, the activity of new drugs against the protein can be studied.[35]

Polymerase chain reaction (PCR) is an extremely versatile technique for copying DNA. In brief, PCR allows a specific DNA sequence to be copied or modified in predetermined ways. The reaction is extremely powerful and under perfect conditions could amplify one DNA molecule to become 1.07 billion molecules in less than two hours. PCR has many applications, including the study of gene expression, the detection of pathogenic microorganisms, the detection of genetic mutations, and the introduction of mutations to DNA.[36] The PCR technique can be used to introduce restriction enzyme sites to ends of DNA molecules, or to mutate particular bases of DNA, the latter is a method referred to as site-directed mutagenesis. PCR can also be used to determine whether a particular DNA fragment is found in a cDNA library. PCR has many variations, like reverse transcription PCR (RT-PCR) for amplification of RNA, and, more recently, quantitative PCR which allow for quantitative measurement of DNA or RNA molecules.[37][38]

Gel electrophoresis is a technique which separates molecules by their size using an agarose or polyacrylamide gel.[39] This technique is one of the principal tools of molecular biology. The basic principle is that DNA fragments can be separated by applying an electric current across the gel - because the DNA backbone contains negatively charged phosphate groups, the DNA will migrate through the agarose gel towards the positive end of the current.[39] Proteins can also be separated on the basis of size using an SDS-PAGE gel, or on the basis of size and their electric charge by using what is known as a 2D gel electrophoresis.[40]

The Bradford assay is a molecular biology technique which enables the fast, accurate quantitation of protein molecules utilizing the unique properties of a dye called Coomassie Brilliant Blue G-250.[41] Coomassie Blue undergoes a visible color shift from reddish-brown to bright blue upon binding to protein.[41] In its unstable, cationic state, Coomassie Blue has a background wavelength of 465nm and gives off a reddish-brown color.[42] When Coomassie Blue binds to protein in an acidic solution, the background wavelength shifts to 595nm and the dye gives off a bright blue color.[42] Proteins in the assay bind Coomassie blue in about 2 minutes, and the protein-dye complex is stable for about an hour, although it is recommended that absorbance readings are taken within 5 to 20 minutes of reaction initiation.[41] The concentration of protein in the Bradford assay can then be measured using a visible light spectrophotometer, and therefore does not require extensive equipment.[42]

This method was developed in 1975 by Marion M. Bradford, and has enabled significantly faster, more accurate protein quantitation compared to previous methods: the Lowry procedure and the biuret assay.[41] Unlike the previous methods, the Bradford assay is not susceptible to interference by several non-protein molecules, including ethanol, sodium chloride, and magnesium chloride.[41] However, it is susceptible to influence by strong alkaline buffering agents, such as sodium dodecyl sulfate (SDS).[41]

The terms northern, western and eastern blotting are derived from what initially was a molecular biology joke that played on the term Southern blotting, after the technique described by Edwin Southern for the hybridisation of blotted DNA. Patricia Thomas, developer of the RNA blot which then became known as the northern blot, actually did not use the term.[43]

Named after its inventor, biologist Edwin Southern, the Southern blot is a method for probing for the presence of a specific DNA sequence within a DNA sample. DNA samples before or after restriction enzyme (restriction endonuclease) digestion are separated by gel electrophoresis and then transferred to a membrane by blotting via capillary action. The membrane is then exposed to a labeled DNA probe that has a complement base sequence to the sequence on the DNA of interest.[44] Southern blotting is less commonly used in laboratory science due to the capacity of other techniques, such as PCR, to detect specific DNA sequences from DNA samples. These blots are still used for some applications, however, such as measuring transgene copy number in transgenic mice or in the engineering of gene knockout embryonic stem cell lines.[30]

The northern blot is used to study the presence of specific RNA molecules as relative comparison among a set of different samples of RNA. It is essentially a combination of denaturing RNA gel electrophoresis, and a blot. In this process RNA is separated based on size and is then transferred to a membrane that is then probed with a labeled complement of a sequence of interest. The results may be visualized through a variety of ways depending on the label used; however, most result in the revelation of bands representing the sizes of the RNA detected in sample. The intensity of these bands is related to the amount of the target RNA in the samples analyzed. The procedure is commonly used to study when and how much gene expression is occurring by measuring how much of that RNA is present in different samples, assuming that no post-transcriptional regulation occurs and that the levels of mRNA reflect proportional levels of the corresponding protein being produced. It is one of the most basic tools for determining at what time, and under what conditions, certain genes are expressed in living tissues.[45][46]

A western blot is a technique by which specific proteins can be detected from a mixture of proteins.[47] Western blots can be used to determine the size of isolated proteins, as well as to quantify their expression.[48] In western blotting, proteins are first separated by size, in a thin gel sandwiched between two glass plates in a technique known as SDS-PAGE. The proteins in the gel are then transferred to a polyvinylidene fluoride (PVDF), nitrocellulose, nylon, or other support membrane. This membrane can then be probed with solutions of antibodies. Antibodies that specifically bind to the protein of interest can then be visualized by a variety of techniques, including colored products, chemiluminescence, or autoradiography. Often, the antibodies are labeled with enzymes. When a chemiluminescent substrate is exposed to the enzyme it allows detection. Using western blotting techniques allows not only detection but also quantitative analysis. Analogous methods to western blotting can be used to directly stain specific proteins in live cells or tissue sections.[47][49]

The eastern blotting technique is used to detect post-translational modification of proteins. Proteins blotted on to the PVDF or nitrocellulose membrane are probed for modifications using specific substrates.[50]

A DNA microarray is a collection of spots attached to a solid support such as a microscope slide where each spot contains one or more single-stranded DNA oligonucleotide fragments. Arrays make it possible to put down large quantities of very small (100 micrometre diameter) spots on a single slide. Each spot has a DNA fragment molecule that is complementary to a single DNA sequence. A variation of this technique allows the gene expression of an organism at a particular stage in development to be qualified (expression profiling). In this technique the RNA in a tissue is isolated and converted to labeled complementary DNA (cDNA). This cDNA is then hybridized to the fragments on the array and visualization of the hybridization can be done. Since multiple arrays can be made with exactly the same position of fragments, they are particularly useful for comparing the gene expression of two different tissues, such as a healthy and cancerous tissue. Also, one can measure what genes are expressed and how that expression changes with time or with other factors.There are many different ways to fabricate microarrays; the most common are silicon chips, microscope slides with spots of ~100 micrometre diameter, custom arrays, and arrays with larger spots on porous membranes (macroarrays). There can be anywhere from 100 spots to more than 10,000 on a given array. Arrays can also be made with molecules other than DNA.[51][52][53][54]

Allele-specific oligonucleotide (ASO) is a technique that allows detection of single base mutations without the need for PCR or gel electrophoresis. Short (2025 nucleotides in length), labeled probes are exposed to the non-fragmented target DNA, hybridization occurs with high specificity due to the short length of the probes and even a single base change will hinder hybridization. The target DNA is then washed and the unhybridized probes are removed. The target DNA is then analyzed for the presence of the probe via radioactivity or fluorescence. In this experiment, as in most molecular biology techniques, a control must be used to ensure successful experimentation.[55][56]

In molecular biology, procedures and technologies are continually being developed and older technologies abandoned. For example, before the advent of DNA gel electrophoresis (agarose or polyacrylamide), the size of DNA molecules was typically determined by rate sedimentation in sucrose gradients, a slow and labor-intensive technique requiring expensive instrumentation; prior to sucrose gradients, viscometry was used. Aside from their historical interest, it is often worth knowing about older technology, as it is occasionally useful to solve another new problem for which the newer technique is inappropriate.[57]

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Molecular biology - Wikipedia

Students seeking admission to the Genetics, Molecular and Cell Biology (GMCB) program apply to the Graduate School of Biomedical Sciences and select the GMCB program. Students interested in the Mammalian Genetics at JAX track must select this track when they apply to GMCB.

Prospective applicants are evaluated based on prior grades, three letters of recommendation, and personal statements. Prior research experience is strongly valued but is not required.

A personal interview is an important part of our evaluation process and may be conducted in person or virtually. An undergraduate major in the biological or life sciences is recommended, but not required.

The GRE is not required but can be submitted with the application.

The application is completed online on the GSBS Application Portal.

Information about application deadlines and the application process can be found in the Admissions section of this website.

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Genetics, Molecular & Cellular Biology Admissions