Control of the lac operon and lactose utilization in bacteria is (check all that apply)
A)not induced in the presence of both glucose and lactose.
B)only induced when there is glucose but not lactose.
C)is a negative control,mediated by a repressor.
D)controlled by the expression of three downstream genes.
E)preferentially utilizing lactose as a carbon source.

Question

Quizplus · Accepted Answer

- A) The lac operon is not induced in the presence of both glucose and lactose because glucose represses the lac operon through catabolite repression, making the bacteria use glucose first.- C) The lac operon is indeed a classic example of negative control, where the lac repressor binds to the operator region in the absence of lactose, preventing transcription.- D) The lac operon controls the expression of three downstream genes (lacZ, lacY, and lacA) involved in lactose metabolism.

Control of the Lac Operon and Lactose Utilization in Bacteria