Jacob, Lwoff, and Monod are best known for their explanation of gene expression; that is, whether a gene is "on" and its instructions are carried out by the cell's ribosomes, or whether it is "off" and ignored. For their work, they received the 1965 Nobel Prize for physiology or medicine.

François Jacob was born in June 1920 in Nancy, Meurthe-et-Moselle, France. He intended to be a surgeon, but injuries he sustained during World War II prevented this, and he switched to research. He received his M.D. in 1947 from the University of Paris and his Doctor of Science in 1954 from the Sorbonne. He then joined the faculty of the Pasteur Institute, becoming head of the Department of Cellular Genetics in 1960. He became a professor of cellular genetics at the College de France in 1964.

Andre Lwoff was born on May 8, 1902, in Ainay-le-Château, Allier, France. After undergraduate studies...