Women in Science: Barbara McClintock and the Discovery of Jumping Genes

Image: Barbara McClintock in her laboratory in 1947. Credit: Smithsonian Institution.

Barbara McClintock was born 118 years ago, 16 June 1902, in Hartford, Connecticut (US). The girl showed great interest in science and research already from a young age. However, her family had little money and was skeptical. They thought that it was better for her to marry and be financially secure.

Nevertheless, her father, a physician, supported her wishes in the end and in 1919, McClintock started a degree in Biology at Cornell University, New York (US). Six years later, she received her Master’s degree and in 1927 her PhD in genetics and zoology.

During her PhD studies, McClintock started the research that would shape her entire career. She began investigating the DNA of corn. For this work, microscopes and colouring techniques were used to identify and analyse individual corn chromosomes. (= long strands of DNA found in each living cell). In 1933, McClintock and her colleague, Harriet Creighton, published important results showing that chromosomes are the basis of genetics.

We need to keep in mind that McClintock conducted these experiments long before the structure of DNA was even discovered in 1952. This gives us an idea about how difficult and sophisticated her work must have been.

After a spell at the University of Missouri (1936-1941), McClintock moved to Long Island, New York to work at the Cold Spring Harbor Laboratory. She would stay for the rest of her professional life and conduct her most important research here.

In the 1940s and 50s, McClintock experimented with the colours of kernels on corn. This work led to the discovery that genetic information is not fixed. McClintock isolated two genes (= short sections of DNA) that controlled kernel colour and showed that they could move along a chromosome to different places. She also proved that these changes could affect neighbouring genes on the chromosome.

In 1983, McClintock received the Nobel Prize in Physiology or Medicine ”for her discovery of mobile genetic elements”. Popular science would come to call these moving genetic elements ”jumping genes”.

Barbara McClintock died 2 September 1992 in Huntington, New York (US).


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