Jacob, Frančois (1920-) is a French biochemist and geneticist. He received the 1965 Nobel Prize in physiology or medicine for his contributions to scientific knowledge of the fundamental processes in living matter that form the bases for such biological principles as adaptation, reproduction, and evolution. Jacob shared the prize with two of his research partners, the French scientists André Lwoff and Jacques Monod. The three men studied the cells of bacteria and discovered in them certain kinds of genes, called regulator genes, that control the activity of other genes.

Jacob was born on June 17, 1920, in Nancy, France. He was educated at the Lycée Carnot in Paris. In the late 1930's, he began to study medicine at the University of Paris (the Sorbonne). From 1940 to 1945, during World War II (1939–1945), he served with the Free French forces. His hands were wounded in battle too severely for him to continue his plan to become a surgeon. He nevertheless earned a medical degree in 1947 and a doctor of science degree in 1954, both from the Sorbonne.

Jacob joined the Pasteur Institute in Paris in 1950 as a research assistant to Lwoff. Jacob became the institute's laboratory director in 1956. He began working with Monod in 1958, and by the end of the decade, they discovered messenger ribonucleic acid (mRNA), an important cell molecule. It copies chemical instructions for making proteins from deoxyribonucleic acid (DNA), another important molecule, and carries them to protein-making cell structures called ribosomes .

From 1960 to 1991, Jacob was head of the Pasteur Institute's department of cell genetics. From 1964 to 1992, he also was professor and chair of the cellular genetics department at the Collège de France in Paris. Jacob published his autobiography, La statue intérieure (The Statue Within), in 1987.