Which of the following turns off transcription by binding to the operator?
A)RNA polymerase
B)repressor
C)promoter
D)lactose

Question

Quizplus · Accepted Answer

The repressor protein binds to the operator, which is the region of DNA adjacent to the promoter that controls access of RNA polymerase to the gene. When the repressor is bound to the operator, it prevents RNA polymerase from transcribing the gene, effectively turning off transcription. Lactose is involved in the regulation of the lac operon in E. coli, but it does not directly turn off transcription - instead, it binds to the repressor protein, causing a conformational change that prevents it from binding to the operator. RNA polymerase is the enzyme responsible for transcription, so it cannot turn off transcription. The promoter is the region of DNA where RNA polymerase binds to initiate transcription, so it is not involved in turning off transcription.

Which of the Following Turns Off Transcription by Binding to the Operator