For a repressible operon to be transcribed, which of the following conditions must occur?
A) A corepressor must be present.
B) RNA polymerase and the active repressor must be present.
C) RNA polymerase must bind to the promoter, and the repressor must be inactive.
D) RNA polymerase must not occupy the promoter, and the repressor must be inactive.

Question

Quizplus · Accepted Answer

In a repressible operon, the repressor is normally active and prevents transcription, but it can be inactivated by a specific molecule called a corepressor. When a corepressor is present, it binds to the repressor, causing it to change shape and lose its ability to bind to the operator. This allows RNA polymerase to bind to the promoter and initiate transcription of the operon. Therefore, for the operon to be transcribed, RNA polymerase must bind to the promoter, and the repressor must be inactive.

For a Repressible Operon to Be Transcribed, Which of the Following