Harriet Creighton was a geneticist who discovered that genes are located on chromosomes. She worked with Barbara McClintock to prove this theory and showed that the recombination of genes on a chromosome requires the exchange of chromosome segments with its partner.
Creighton was born in Illinious, USA in 1909 and attended Wellesley College in Massachusetts, receiving her bachelor of arts degree in 1929. She then became a botany graduate student and laboratory assistant at Cornell University. Barbara McClintock, a future Nobel Prize winner was also working at Cornell University as a lecturer. McClintock and Creighton became friends and started to investigate how chromosomes carry and exchange genetic material. They hypothesised that chromosomes carried and exchanged genetic material in order to produce new combinations of physical traits, however there was no evidence to prove this theory.
They began to study a unique corn strain (Zea mays), which has a ninth chromosome which produces a waxy, purple kernel, and they planted the kernels from this strain. They then fertilised the silks with pollen samples, which were taken from a plant which did not produce waxy, purple kernels. After the ears of the corn were harvested, they found that a proportion of the kernels were, in fact, waxy or purple, having inherited either trait, but not both. McClintock and Creighton concluded that the two genes much have become separated. In fact, after examination, they observed that the chromosomes had crossed over, and exchanged segments, this proved their theory of the genes for physical traits being carried on chromosomes.
McClintock and Creighton were the first scientists to prove that segments of genetic material on chromatids of homologous chromosomes cross over during meiosis.
After completing her PhD in botany from Cornell University in 1933, she became assistant professor of botany at Connecticut College in 1934. From 1950 to 1955, Creighton became the first female secretary of the Botanical Society of America, serving again as vice president in 1955 and president in 1956.
Creighton became a fellow of the American Association for the Advancement of Science (AAAS), and became vice president of the Botanical Sciences Section in 1964.
Creighton continued to work in plant genetics, focussing on the problems of heredity in corn, and ‘mad begonia’s weird growth patterns.