Question

DNA transposons and retrotransposons are similar:

		they both have poly-A segments at one end.
		both can encode an enzyme required for mobilization.
		transposition results in movement of the original transposon to a different place in the genome, losing the previous spot.
		during transposition, both go through an RNA form that is copied back into DNA.

Answer 1

both can encode an enzyme required for mobilization.

Transposon, class of genetic elements that can “jump” to different locations within a genome. Although these elements are frequently called “jumping genes,” they are always maintained in an integrated site in the genome. In addition, most transposons eventually become inactive and no longer move.

Transposons are mutagens. They can cause mutations in several ways: If a transposon inserts itself into a functional gene, it will probably damage it. Insertion into exons, introns, and even into DNA flanking the genes (which may contain promoters and enhancers) can destroy or alter the gene's activity.

Barbara McClintock discovered genetic elements of mobile nature referred as the “jumping genes.” Before her findings, genes were accepted as being static, with fixed locations in which cells were organized like a library. Her significant discovery in terms of the mobility of genes pioneered a new light on the workings of DNA.

The retrotransposons' replicative mode of transposition by means of an RNA intermediate rapidly increases the copy numbers of elements and thereby can increase genome size. Like DNA transposable elements (class II transposons), retrotransposons can induce mutations by inserting near or within genes.

There are two main types of retrotransposon, long terminal repeats (LTRs) and non-long terminal repeats (non-LTRs). Retrotransposons are classified based on sequence and method of transposition. Most retrotransposons in the maize genome are LTR, whereas in humans they are mostly non-LTR. Retrotransposons (mostly of the LTR type) can be passed onto the next generation of a host species through the germline.