The cAMP receptor protein (CRP) is said to be responsible for positive regulation of the lac operon because ________.
A) CRP binds cAMP
B) CRP binds to the CAP-binding site
C) CRP prevents binding of the repressor to the operator
D) CRP bound to the CRP-binding site stimulates the transcription of the lac operon

Question

Quizplus · Accepted Answer

CRP bound to the CRP-binding site stimulates the transcription of the lac operon. The presence of cAMP is necessary for CRP to bind to its CRP-binding site and activate transcription. The repressor protein binds to the operator and prevents RNA polymerase from initiating transcription, but CRP works in conjunction with cAMP to stimulate transcription by helping RNA polymerase bind to the promoter region. Therefore, option D is the best choice. Choices A, B, and C are incorrect.

The CAMP Receptor Protein (CRP) Is Said to Be Responsible