In the presence of glucose, the lac operon
A) is induced.
B) is inhibited.
C) the effect of glucose is dependent on the presence or absence of lactose.
D) the catabolite activator protein (CAP) binds glucose and expression is inhibited.
E) glucose has no effect on the lac operon which is specific for lactose metabolism.

Question

Quizplus · Accepted Answer

In the presence of glucose, the lac operon is inhibited because glucose represses the lac operon by preventing the catabolite activator protein (CAP) from binding to the promoter region, which is necessary for the activation of the operon. This phenomenon is known as catabolite repression.

In the Presence of Glucose, the Lac Operon