Chapter 14 : The Messenger

Abstract:

The two-month lab course designed by Jacques Monod in 1956 and 1957 was intended to breach the gap between university teaching and living research. It was the author's real introduction to what was to become molecular biology—covering DNA, proteins, physiology, and biochemistry of bacteria and phages. The study of cross-reacting material (CRM) was of course prompted by the need to map the structural gene for galactosidase so it could be distinguished from genes involved in induction. But it was also to understand the obscure relation between that old ghost Pz and CRM of galactosidase. A scheme of competition between galactosidase and CRM was devised in which the only thing measured was enzyme activity. The is mutant which became a cornerstone of the theory of induction by negative control appeared by luck. It was a strange lac negative, giving numerous revertants which were all constitutive. It proved to be trans-dominant and fit nicely with the theory.