What is INSERTIONAL MUTAGENESIS? What does INSERTIONAL MUTAGENESIS mean?

SUPPORT The Audiopedia using it with our Android app - https://ift.tt/2r4nBUo What is INSERTIONAL MUTAGENESIS? What does INSERTIONAL MUTAGENESIS mean? INSERTIONAL MUTAGENESIS meaning - INSERTIONAL MUTAGENESIS definition - INSERTIONAL MUTAGENESIS explanation. Source: Wikipedia.org article, adapted under https://ift.tt/yjiNZw license. In molecular biology, insertional mutagenesis is the creation of mutations of DNA by the addition of one or more base pairs. Such insertional mutations can occur naturally, mediated by viruses or transposons, or can be artificially created for research purposes in the lab. Signature tagged mutagenesis is a technique used to study the function of genes. A transposon such as the P element of Drosophila melanogaster is allowed to integrate at random locations in the genome of the organism being studied. Mutants generated by this method are then screened for any unusual phenotypes. If such a phenotype is found then it can be assumed that the insertion has caused the gene relating to the usual phenotype to be inactivated. Because the sequence of the transposon is known, the gene can be identified, either by sequencing the whole genome and searching for the sequence, or using the polymerase chain reaction to amplify specifically that gene. Because many viruses integrate their own genomes into the genomes of their host cells in order to replicate, mutagenesis caused by viral infections is a fairly common occurrence. Not all integrating viruses cause insertional mutagenesis, however. Some DNA insertions will lead to no noticeable mutation. In recent gene therapy trials, the lentiviral vectors used to insert therapeutic DNA showed no tendency to disrupt gene function or promote oncogenic development. Because of these advances, it is now considered safe to use such integrating vectors for gene therapy. An advantage is that the lentiviral vectors integrate the DNA permanently, whereas other, non-integrating, viruses' effect is transient. For those viruses such as gammaretroviruses that tend to integrate their DNA in genetically unfavorable locations, the severity of any ensuing mutation depends entirely on the location within the host's genome wherein the viral DNA is inserted. If the DNA is inserted into the middle of an essential gene, the effects on the cell will be drastic. Additionally, insertion into a gene's promoter region can have equally drastic effects. Likewise, if the viral DNA is inserted into a repressor, the promoter's corresponding gene may be over-expressed – leading to an overabundance of its product and altered cellular activity. If the DNA is inserted into a gene's enhancer region, the gene may be under-expressed – leading to relative absence of its product, which can significantly interrupt the activity of the cell. Alteration of different genes will have varying effects on the cell. Not all mutations will significantly affect the proliferation of the cell. However, if the insertion occurs in an essential gene or a gene that is involved in cellular replication or programmed cell death, the insertion may compromise the viability of the cell or even cause the cell to replicate interminably – leading to the formation of a tumor, which may become cancerous.....