Barbara McClintock (1902-1992) was a scientist and cytogeneticist who discovered the “jumping gene”, focusing on maize as a model organism. She received a B.S. in 1923 from Cornell’s College of Agriculture, an M.S. in botany in 1925, and finished her Ph.D. in the new field of cytogenetics in 1927. To continue her research on corn chromosomes, she remained at Cornell as a professor, where she met Harriet Creighton in 1929. McClintock and Creighton worked together to prove the occurrence of chromosomal crossovers in corn, and that it increases genetic variation in the species. She studied the effects of X-rays, and how to cause mutations, on corn chromosomes, which led to her discovery of translocations, inversions, deletions and ring chromosomes in corn. She developed the first genetic map for maize, where she linked chromosomes to physical traits, and proved that genetic information can be suppressed between generations. She taught at the University of Missouri for five years, but felt that she would never be promoted. She left to join Marcus Rhoades and Milislav Demerec at Cold Spring Harbor Laboratory, where she discovered the process of transposition (jumping genes) in corn chromosomes, the switching on or off of physical traits during reproduction. She stayed at Cold Spring Harbor until her death in 1992. She was the only woman to receive an unshared Nobel Prize for Physiology or Medicine, for the discovery of genetic transposition in 1983.