Which of the following events are necessary for efficient expression of the lac operon?
(I)The lac repressor must bind inducer and dissociate from the operator site.
(II)CAP must bind cAMP.
(III)CAP and the repressor must simultaneously bind to RNAP.
A)I,II,III
B)I,II
C)I,III
D)II,III
E)I only

Question

Quizplus · Accepted Answer

For efficient expression of the lac operon, two main events are necessary: (I) The lac repressor must bind to the inducer (usually allolactose, a lactose derivative) and dissociate from the operator site, which prevents it from blocking transcription. (II) CAP (catabolite activator protein) must bind cAMP (cyclic AMP), which occurs when glucose levels are low, facilitating the binding of RNA polymerase to the promoter and enhancing transcription. (III) is not a requirement for efficient expression; CAP and the repressor do not need to simultaneously bind to RNA polymerase (RNAP).

Which of the Following Events Are Necessary for Efficient Expression