Jacques Monod, French biochemist and geneticist, Nobel Prize laureate (d. 1976)
Jacques Lucien Monod (February 9, 1910 – May 31, 1976) was a French biochemist who won the Nobel Prize in Physiology or Medicine in 1965, sharing it with François Jacob and André Lwoff "for their discoveries concerning genetic control of enzyme and virus synthesis".Monod and Jacob became famous for their work on the E. coli lac operon, which encodes proteins necessary for the transport and breakdown of the sugar lactose (lac). From their own work and the work of others, they came up with a model for how the levels of some proteins in a cell are controlled. In their model, the manufacture of proteins, such as the ones encoded within the lac (lactose) operon, is prevented when a repressor, encoded by a regulatory gene, binds to its operator, a specific site in the DNA sequence that is close to the genes encoding the proteins. (It is now known that a repressor bound to an operator physically blocks RNA polymerase from binding to the promoter, the site where transcription of the adjacent genes begins.)

Study of the control of expression of genes in the lac operon provided the first example of a system for the regulation of transcription. Monod also suggested the existence of messenger RNA molecules that link the information encoded in DNA and proteins. For these contributions he is widely regarded as one of the founders of molecular biology.