How does the lac repressor inhibit transcription?
A) It binds to the RNA polymerase and prevents its association to the DNA.
B) It binds to the DNA and prevents the RNA polymerase from unwinding and transcribing the DNA.
C) It binds to RNA polymerase and causes a frame shift, thus producing an mRNA with a nonsense mutation.
D) It binds to the mRNA molecule, preventing ribosomes from binding.
E) None of the answers is correct.

Question

Quizplus · Accepted Answer

The lac repressor inhibits transcription by binding to the operator region of the DNA, which is located near the promoter. This binding physically blocks RNA polymerase from accessing the promoter, thus preventing it from unwinding the DNA and initiating transcription.

How Does the Lac Repressor Inhibit Transcription