The mechanism by which the presence of glucose inhibits the lac operon is

Question

Quizplus · Accepted Answer

The mechanism by which the presence of glucose inhibits the lac operon is through a process called catabolite repression. Glucose is the preferred energy source for bacteria and therefore, if glucose is present, the lac operon is repressed to prevent the unnecessary use of lactose as an energy source. This repression involves the binding of catabolite activator protein (CAP) to the lac operon promoter site in the absence of glucose. However, in the presence of glucose, cAMP (cyclic adenosine monophosphate) levels are reduced which reduces the binding of CAP to the promoter site and thereby represses the lac operon.

The Mechanism by Which the Presence of Glucose Inhibits the Lac