In positive control of several sugar metabolism-related operons, the cAMP receptor protein (CRP) binds to DNA to stimulate transcription. Which of the following environmental conditions causes an increase in CRP activity in stimulating transcription?
A) an increase in glucose and an increase in cAMP
B) a decrease in glucose and an increase in cAMP
C) an increase in glucose and a decrease in cAMP
D) a decrease in glucose and a decrease in the repressor

Question

Quizplus · Accepted Answer

The CRP protein requires the allosteric activator cAMP to bind to DNA and stimulate transcription. When glucose levels are low, cAMP levels increase, leading to an increase in CRP activity and stimulation of transcription. This is because cells preferentially use glucose as an energy source, so low glucose levels indicate the need for alternative energy sources to be utilized, which are activated by CRP. Therefore, an increase in cAMP and a decrease in glucose, as in choice B, would lead to an increase in CRP activity and stimulation of transcription.

In Positive Control of Several Sugar Metabolism-Related Operons, the CAMP