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Modern Genetic Analysis Chapter 13. Transposable Genetic Elements
Summary

Nature has devised many different ways of changing the genetic architecture of organisms. We are now beginning to understand the molecular processes behind some of these phenomena. Gene mutation, recombination between chromosomes, and transposition can all be reasonably explained at the DNA level. Far from merely producing genetic waste, these processes undoubtedly all have important roles in evolution. This idea is strengthened through the knowledge that the processes themselves are to a large extent under genetic control: there are genes that affect the efficiency of mutation, recombination, and transposition.

Although different mechanisms of transposition are sometimes used, the analogies between the transposable elements of phages, bacteria, and eukaryotes are striking. At present, it is not known if transposons are elements that normally play a role in the day-to-day transactions of the genome, as originally proposed by Barbara McClintock in the 1950s, or if they are pieces of "selfish DNA" that exist for no purpose other than their own survival. Whatever the truth of this matter is, transposons certainly represent a completely unexpected element of chaos in the genome, which geneticists have already harnessed into their team of analytical procedures. At the evolutionary level, transposons may be important in the sudden leaps that characterize the fossil record.

© 1999 by W. H. Freeman and Company. All rights reserved.