Genetic transposition: The ability of genes to change position on chromosomes, a process in which a transposable element is removed from one site and inserted into a second site in the DNA. Genetic transposition was the first type of genetic instability to be discovered.
This remarkable phenomenon was discovered by the great American geneticist Barbara McClintock (1902-1992) who won the 1983 Nobel Prize in Physiology or Medicine "for her discovery of mobile genetic elements." McClintock did her pioneering research in a plant (maize) decades earlier, at a time when the genetic code and the structure of the DNA double helix were not yet known. This type of element has now been found in microorganisms, insects, animals and man and has been demonstrated to have important functions.