Question 6 1 pts In the regulation of the Lac Operon which o

Question 6 1 pts In the regulation of the Lac Operon, which of the following is true when Lactose is present and Glucose is absent? O Neither the CAP activator nor the repressor is bound and transcription is at basal levels. The CAP activator is bound and the repressor is not bound and transcription is activated O The CAP activator is not bound and the repressor is bound and transcription is inhibited. The CAP activator and the repressor are both bound transcription is inhibited

Solution

The answer is option B i.e. The CAP activator is bound and the repressor is not bound and transcriptiion is activated.

Explanation: The two regulators that regulate the lac operon in the presence of lactose and glucose levels are lac repressor and CAP.

Lac repressor usually blocks transcription as it is a lactose sensor; but in the presence of lactose it\'s isomer allolactose can sense the presence indirectly. CAP on the other hand acts as a glucose sensor and in absence of glucose it promotes RNA polymerase binding at the CAP site and promotes transcription. In presence of lactose, the allolactose binds to the lac represson and releases it from the operator site, in turn promoting RNA polymerase to transcribe the operon.