Which of the following is true of the lac operon?
A) it is negatively controlled via the lac repressor, a protein that only binds to DNA in the absence of lactose
B) it is positively controlled via CAP, a protein that is activated by binding to ATP
C) lactose represses the lac operon but this repression can be removed by addition of IPTG
D) binding of lactose (or an analog of lactose) increases the affinity of the lac repressor for DNA
E) none of the above

Question

Quizplus · Accepted Answer

The lac operon is negatively controlled by the lac repressor, which binds to the operator region of the operon in the absence of lactose, preventing transcription. When lactose is present, it binds to the repressor, causing it to release from the DNA, allowing transcription to proceed.

Which of the Following Is True of the Lac Operon