nonautonomous elements do not have transposase or reverse transcriptase and need it from other elements. If a transposable element or transposon jumps to the inside of another gene, this can result in a mutation. Others will cause cancer from mutations. It is surmised that transposable elements are partly responsible for human diseases. Most transposons are, however, silent and do not cause any particular disease state. Things like DNA methylation and chromatin remodeling will sometimes render the transposon unable to actually transcribe or be active. There is a type of RNA called small interfering RNA or siRNA. It is a type of RNA that can be made by transposons and can prevent transposition. This means that transposons can mediate their own silencing. It is not completely clear how it does this but it can form a piece of double-stranded RNA; if this process is blocked, there is more movement of the transposon. Transposons are not completely destructive. They can drive the evolutionary process by moving exons around and by inserting into certain genes on the organism’s DNA. In essence, they can allow for certain genetic traits to be uncovered through the inbreeding of some species of plants or animals.
GENOMICS We have already been discussing genomics, which is the study of DNA; however, we have not yet talked about the branch of DNA concerned with gene sequencing, which is also a part of genomics. In gene sequencing, DNA polymerase is used to generate a brand-new strand of DNA after splitting up an existing strand. The new DNA strand is tagged with fluorescence so that a sequence of up to 125 genes can be read at one time. Overlapping segments are read so that the entire gene can be read over a period of time. Researchers do this in order to map genes and look for gene variations or mutations in a genome. Mutations can involve a substitution, deletion, or addition of one or a couple of base pairs; they can also involve deletions of many thousands of bases at a time.
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