Interspersed Repeat

Interspersed Repeat

Interspersed repetitive DNA is found in all eukaryotic genomes. Certain classes of these sequences propagate themselves by RNA mediated transposition, and they have been called retrotransposons. Interspersed repetitive DNA elements allow new genes to evolve. They do this by uncoupling similar DNA sequences from gene conversion during meiosis. The recombinational events of meiosis create heteroduplexes composed of strands from each parental chromosome. These heteroduplexes lead to mismatch repair. The net result is the homogenization and elimination of sequence differences during meiosis. Gene conversion can be viewed as the force acting to create sequence identity within the gene pool of a species. This is a cohesive force acting to match up DNA sequences of individual organisms that comprise a species. In effect the gene conversion causes the DNA sequences to clump together within a species and by doing so creates the natural boundaries between species. The gene pool of a species consists of DNA sequences linked in a network by gene conversion events. Interspersed repeat DNA constitutes 25–40% of most mammalian genomes.