Barbara McClintock

Barbara McClintock was an American scientist who discovered transposable elements, informally called jumping genes, in maize during the 1940s and 1950s. Working with colored kernel patterns she could track visually across generations, she showed that segments of the genome can move from one chromosomal location to another and switch nearby genes on or off, a finding that ran against the assumption that genes sit in fixed positions. The idea was met with skepticism for decades until molecular techniques confirmed it in other organisms, and she was awarded the unshared 1983 Nobel Prize in Physiology or Medicine for the discovery.