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Barbara McClintock (June 16, 1902 – September 2, 1992) was an American scientist and cytogeneticist who was awarded the 1983 Nobel Prize in Physiology or Medicine. McClintock received her PhD in botany from Cornell University in 1927. There she started her career as the leader of the development of maize cytogenetics, the focus of her research for the rest of her life. From the late 1920s, McClintock studied chromosomes and how they change during reproduction in maize. She developed the technique for visualizing maize chromosomes and used microscopic analysis to demonstrate many fundamental genetic ideas. One of those ideas was the notion of genetic recombination by crossing-over during meiosis—a mechanism by which chromosomes exchange information. She produced the first genetic map for maize, linking regions of the chromosome to physical traits. She demonstrated the role of the telomere and centromere, regions of the chromosome that are important in the conservation of genetic information. She was recognized as among the best in the field, awarded prestigious fellowships, and elected a member of the National Academy of Sciences in 1944. During the 1940s and 1950s, McClintock discovered transposons and used it to demonstrate that genes are responsible for turning physical characteristics on and off. She developed theories to explain the suppression and expression of genetic information from one generation of maize plants to the next. Due to skepticism of her research and its implications, she stopped publishing her data in 1953. Later, she made an extensive study of the cytogenetics and ethnobotany of maize races from South America. McClintock's research became well understood in the 1960s and 1970s, as other scientists confirmed the mechanisms of genetic change and protein expression that she had demonstrated in her maize research in the 1940s and 1950s. Awards and recognition for her contributions to the field followed, including the Nobel Prize in Physiology or Medicine, awarded to her in 1983 for the discovery of genetic transposition; as of 2023, she remains the only woman who has received an unshared Nobel Prize in that category. Early life Barbara McClintock was born Eleanor McClintock on June 16, 1902, in Hartford, Connecticut, the third of four children born to homeopathic physician Thomas Henry McClintock and Sara Handy McClintock. Thomas McClintock was the child of British immigrants. Marjorie, the oldest child, was born in October 1898; Mignon, the second daughter, was born in November 1900. The youngest, Malcolm Rider (called Tom), was born 18 months after Barbara. When she was a young girl, her parents determined that Eleanor, a "feminine" and "delicate" name, was not appropriate for her, and chose Barbara instead. McClintock was an independent child beginning at a very young age, a trait she later identified as her "capacity to be alone". From the age of three until she began school, McClintock lived with an aunt and uncle in Brooklyn, New York, in order to reduce the financial burden on her parents while her father established his medical practice. She was described as a solitary and independent child. She was close to her father, but had a difficult relationship with her mother, tension that began when she was young. The McClintock family moved to Brooklyn in 1908 and McClintock completed her secondary education there at Erasmus Hall High School; she graduated early in 1919. She discovered her love of science and reaffirmed her solitary personality during high school. She wanted to continue her studies at Cornell University's College of Agriculture. Her mother resisted sending McClintock to college for fear that she would be unmarriageable, a common attitude at the time. McClintock was almost prevented from starting college, but her father allowed her to just before registration began, and she matriculated at Cornell in 1919. Education and research at Cornell McClintock began her studies at Cornell's College of Agriculture in 1919. There, she participated in student government and was invited to join a sorority, though she soon realized that she preferred not to join formal organizations. Instead, McClintock took up music, specifically jazz. She studied botany, receiving a BSc in 1923. Her interest in genetics began when she took her first course in that field in 1921. The course was based on a similar one offered at Harvard University, and was taught by C. B. Hutchison, a plant breeder and geneticist. Hutchison was impressed by McClintock's interest, and telephoned to invite her to participate in the graduate genetics course at Cornell in 1922. McClintock pointed to Hutchison's invitation as a catalyst for her interest in genetics: "Obviously, this telephone call cast the die for my future. I remained with genetics thereafter." Although it has been reported that women could not major in genetics at Cornell, and therefore her MS and PhD—earned in 1925 and 1927, respectively—were officially awarded in botany, recent research has revealed that women were permitted to earn graduate degrees in Cornell's Plant Breeding Department during the time that McClintock was a student at Cornell. During her graduate studies and postgraduate appointment as a botany instructor, McClintock was instrumental in assembling a group that studied the new field of cytogenetics in maize. This group brought together plant breeders and cytologists, and included Marcus Rhoades, future Nobel laureate George Beadle, and Harriet Creighton. Rollins A. Emerson, head of the Plant Breeding Department, supported these efforts, although he was not a cytologist himself. She also worked as a research assistant for Lowell Fitz Randolph and then for Lester W. Sharp, both Cornell botanists. McClintock's cytogenetic research focused on developing ways to visualize and characterize maize chromosomes. This particular part of her work influenced a generation of students, as it was included in most textbooks. She also developed a technique using carmine staining to visualize maize chromosomes, and showed for the first time the morphology of the 10 maize chromosomes. This discovery was made because she observed cells from the microspore as opposed to the root tip. By studying the morphology of the chromosomes, McClintock was able to link specific chromosome groups of traits that were inherited together. Marcus Rhoades noted that McClintock's 1929 Genetics paper on the characterization of triploid maize chromosomes triggered scientific interest in maize cytogenetics, and attributed to her 10 of the 17 significant advances in the field that were made by Cornell scientists between 1929 and 1935. In 1930, McClintock was the first person to describe the cross-shaped interaction of homologous chromosomes during meiosis. The following year, McClintock and Creighton proved the link between chromosomal crossover during meiosis and the recombination of genetic traits. They observed how the recomb.... Discover the Sandra Rosensteil popular books. Find the top 100 most popular Sandra Rosensteil books.