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Molecular genetics – Wikipedia, the free encyclopedia

May 19th, 2015 6:50 pm

Molecular genetics is the field of biology and genetics that studies the structure and function of genes at a molecular level. Molecular genetics employs the methods of genetics and molecular biology to elucidate molecular function and interactions among genes. It is so called to differentiate it from other sub fields of genetics such as ecological genetics and population genetics.

Along with determining the pattern of descendants, molecular genetics helps in understanding developmental biology, genetic mutations that can cause certain types of diseases. Through utilizing the methods of genetics and molecular biology, molecular genetics discovers the reasons why traits are carried on and how and why some may mutate.

One of the first tools available to molecular geneticists is the forward genetic screen. The aim of this technique is to identify mutations that produce a certain phenotype. A mutagen is very often used to accelerate this process. Once mutants have been isolated, the mutated genes can be molecularly identified.

Forward saturation genetics is a method for treating organisms with a mutagen, then screens the organism's offspring for particular phenotypes. This type of genetic screening is used to find and identify all the genes involved in a trait.[1]

While forward genetic screens are productive, a more straightforward approach is to simply determine the phenotype that results from mutating a given gene. This is called reverse genetics. In some organisms, such as yeast and mice, it is possible to induce the deletion of a particular gene, creating what's known as a gene "knockout" - the laboratory origin of so-called "knockout mice" for further study. In other words this process involves the creation of transgenic organisms that do not express a gene of interest. Alternative methods of reverse genetic research include the random induction of DNA deletions and subsequent selection for deletions in a gene of interest, as well as the application of RNA interference.

A mutation in a gene can result in a severe medical condition. A protein encoded by a mutated gene may malfunction and cells that rely on the protein might therefore fail to function properly. This can cause problems for specific tissues or organs, or for the entire body. This might manifest through the course of development (like a cleft palate) or as an abnormal response to stimuli (like a peanut allergy). Conditions related to gene mutations are called genetic disorders. One way to fix such a physiological problem is gene therapy. By adding a corrected copy of the gene, a functional form of the protein can be produced, and affected cells, tissues, and organs may work properly. As opposed to drug-based approaches, gene therapy repairs the underlying genetic defect.

One form of gene therapy is the process of treating or alleviating diseases by genetically modifying the cells of the affected person with a new gene that's functioning properly. When a human disease gene has been recognized molecular genetics tools can be used to explore the process of the gene in both its normal and mutant states. From there, geneticists engineer a new gene that is working correctly. Then the new gene is transferred either in vivo or ex vivo and the body begins to make proteins according to the instructions in that gene. Gene therapy has to be repeated several times for the infected patient to continually be relieved, however, as repeated cell division and cell death slowly randomizes the body's ratio of functional-to-mutant genes.

Currently, gene therapy is still being experimented with and products are not approved by the U.S. Food and Drug Administration. There have been several setbacks in the last 15 years that have restricted further developments in gene therapy. As there are unsuccessful attempts, there continue to be a growing number of successful gene therapy transfers which have furthered the research.

Major diseases that can be treated with gene therapy include viral infections, cancers, and inherited disorders, including immune system disorders.[citation needed]

Classical gene therapy is the approach which delivers genes, via a modified virus or "vector" to the appropriate target cells with a goal of attaining optimal expression of the new, introduced gene. Once inside the patient, the expressed genes are intended to produce a product that the patient lacks, kill diseased cells directly by producing a toxin, or activate the immune system to help the killing of diseased cells. [2]

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Molecular genetics - Wikipedia, the free encyclopedia

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