(1903–89), American biologist and Nobel laureate, noted particularly for his pioneering research on the genetics of sac fungi, such as bread molds.

Beadle was born on Oct. 22, 1903, on a farm near Wahoo, Nebr., and educated at the University of Nebraska and Cornell University, from which he received a doctorate in genetics in 1931. After a stint as a research fellow at the California Institute of Technology (1931–36), he was an assistant professor of genetics at Harvard University (1936–37), a professor at Stanford University (1937–46), and chairman of the division of biology at the California Institute of Technology (1946–61).

Beadle's research focused primarily on the genetics of maize at Cornell and the fruit fly Drosophila at Caltech. At Stanford he continued to work with Drosophila but then turned his attention to the bread mold Neurospora crassa, which had a number of characteristics making it a convenient subject for genetic research. He and his Stanford colleague Edward Lawrie Tatum induced mutations in the mold with X-rays, and their results led to the “one gene, one enzyme” hypothesis—that is, a gene specifies the production of a specific enzyme, or, more generally, a single gene determines the structure of one protein. This notion ultimately turned out to be not entirely accurate, but at the time it was enormously influential and stimulated the development of molecular genetics. Beadle and Tatum's findings, published in the landmark paper “Genetic Control of Biochemical Reactions in Neurospora” (1941), had an immediate impact on the manufacture of penicillin. In recognition of “their discovery that genes act by regulating definite chemical events,” Beadle and Tatum received half of the 1958 Nobel Prize in physiology or medicine. (The American geneticist Joshua Lederberg received the other half of the prize.)

Beadle served as president of the University of Chicago from 1961 to 1968, after which he directed the American Medical Association's Institute for Biochemical Research until 1970. He wrote Introduction to Genetics (with A.H. Sturtevant; 1939); Genetics and Modern Biology (1963); and, with his second wife, Muriel McClure Barnett (1915–94), The Language of Life (1966), which won an award as the year's best science book for youth.

Among other honors, Beadle received the Albert Lasker Award in 1950 “for outstanding and fundamental contributions to the understanding of genetic control of metabolic processes” and the National Award of the American Cancer Society in 1959. He died on June 9, 1989, in Pomona, Calif.