Abstract
Barbara McClintock was a pioneer in cytogenetics, winning the 1983 Nobel Prize for Physiology or Medicine. Studying corn (Zea mays or maize) as a model organism, with a penetrating intellect, outstanding powers of observation, and excruciating attention to detail, she mapped the entire set of corn chromosomes, observed meiosis, and matched heritable traits to specific chromosomes. Crucially, she documented rare but important instances of the transposition of genes along the length of newly replicating chromosomes. She foresaw that while the cell's chromosomal copying mechanisms generally created identical copies, these seemingly random “jumping genes” would ultimately result in mutations. This finding formed part of the foundation of modern genetics.