Barbara McClintock

Image: USNLM Birth: June 16, 1902 Death: September 2, 1992 Specialty: Cytogenetics Major Contributions: Awarded the Nobel Prize in Physiology or Medicine in 1983 Discovered mobile genetic elements First person to describe the cross-shaped interaction of homologous chromosomes during meiosis

Image: USNLM
Birth: June 16, 1902
Death: September 2, 1992
Specialty: Cytogenetics
Major Contributions:
Awarded the Nobel Prize in Physiology or Medicine in 1983
Discovered mobile genetic elements
First person to describe the cross-shaped interaction of homologous chromosomes during meiosis

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Often considered an outsider and rebel, Dr. Barbara McClintock was really more a visionary and very ahead of her time.

Studying botany at Cornell University she earned BS, MS, and doctoral degrees from the school focusing her course work on maize cytogenetics–the study of corn at the cellular level. Beyond the economic incentives to study corn as it is the center of a large agricultural industry, it has the advantage that each kernel is the result of separate genetic cross and provides ample research material.

While at Cornell, McClintock worked with a graduate student on a series of experiments to show that a genetic phenomenon called “crossing-over” has a cellular explanation and they were able to link a genetic trait with a part of a chromosome that was observable under a microscope and demonstrate the physical basis for crossing-over.

Publishing these findings, McClintock was building her reputation in the field and was awarded multiple fellowships for travel and research but she had no offers for full time work, which she found frustrating and disheartening. She was finally offered a fulltime teaching and research position at the University of Missouri where she combined the use of X-rays and corn genetics.  Discovering what she called the “breakage-fusion-bridge” cycle in chromosomes that had been irradiated in 1938, she reaffirmed her status in the field of maize cytogenetics.

Frustrated with her lack of professional opportunities for advancement at the school, she left after five years, accepting a position at the Cold Spring Harbor research facility. Between 1948 and 1950 her experiments showed that she could use specific genes as controllers, turning on and off traits, but this work was so radical that many had trouble understanding it. It would take 32 years after she first presented her findings for the scientific community to fully come on board and in 1983 McClintock was awarded the Nobel Prize in Medicine for her discovery of mobile genetic elements.

Giving informal talks on the history of genetics and mobile genetic elements to junior scientists, she remained a regular presence in the Cold Spring Harbor community until her death in 1992.

Written by Angela Goad

Sources:

Nobel Prizes and Laureates: Barbara McClintock

DNA From the Beginning: Barbara McClintock

Scitable: Barbara McClintock and the Discovery of Jumping Genes (Transposons)

Headstrong: 52 Women Who Changed Science-and the World by Rachel Swaby

See Also:

Wikipedia: Barbara McClintock

Profiles in Science: The Barbara McClintock Papers