Barbara McClintock

For the illustrator named Barbara McClintock see Barbara McClintock (illustrator).

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Barbara McClintock (June 16 1902–September 2 1992) was a pioneering American scientist and one of the World's most distinguished cytogeneticists. She received the Nobel Prize in Physiology or Medicine in 1983 for her discovery of genetic transposition. McClintock received her Ph.D. in botany from Cornell University in 1927, were she was a leader in the development of maize cytogenetics; the field remained the focus of her research for the rest of her career.

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Beginning in the late 1920s, McClintock studied chromosomes and how they changed following reproduction in maize. Her work in the field was groundbreaking; she developed the technique to visualize maize chromosomes and using microscopic analysis demonstrated many fundamental genetic concepts including genetic change by crossing-over during meiosis, she produced the first genetic map for maize linking regions of the chromosome with physical traits, and she demonstrated the role of the telomere, centromere. She was recognized amongst the best in the field, awarded prestigious fellowships and elected a member of the National Academy of Sciences. During the 1940s and 1950s, McClintock discovered transposition and using this system showed how genes were responsible for turning on or off physical characteristics. She developed theories to explain the repression or expression of genetic information from one generation of maize plants. Her concept of a dynamic genome defied mainstream genetics. After encountering skepticism about her research and its implications, she refrained from publishing her data. In her later career she made an extensive study of the cytogenetics and ethnobotany of maize races from South America.

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McClintock's research became well understood in the 1970s and 1980s as researchers demonstrated the mechanisms of genetic change and genetic regulation which she had shown in her maize research in the 1950s. Awards and recognition of her contribution to the field followed, including the Nobel Prize in Physiology and Medicine awarded to her in 1983 when she was 81 years old; she was the first and only woman to receive an unshared Nobel Prize in that category.

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