Question

In E. coli, when glucose levels are high and lactose is present, what, if anything, will remain bound to
the control region of the lac operon?

a. Nothing will remain bound to the lac operon.
b. CAP activator with cAMP, and repressor without lactose inducer.
c. Repressor without lactose inducer only.
d. Repressor with lactose inducer only.
e. CAP activator with cAMP only

Answer 1

please explain why

Answer 2

e. CAP activator with cAMP only
simlply called as catabolic repression.

Answer 3

But the answer is A.

Answer 4

I think catabolite repression is when glucose level is low? But the question says the glucose level is high

Answer 5

a. Nothing will remain bound to the lac operon
yep this is correct one.
Catabolice repression is when glucose high.
Bacteria prefer glucose over lactose.

Answer 6

so when glucose is low, cAMP and CAP will bind on the lac operon?

Answer 7

Yes.
At low glucose level cAMP concentration increses. At high cocentration it activate CAP. (catabolite gene activator protein). It goes and bind to promoter site.
It transcribe lac operon.

Answer 8

srry still have some confusion
isnt the cAMP binds on the CAP then to the promoter?
so how is it low concentration - cAMP increases
high concentration - activate CAP

I thought is cAMP + CAP when low concentration