question_answer

In E. coli. an operator gene combine with :

A) inducer gene to switch on structural gene action

B)  inducer gene to switch off structural gene action

C) regulator protein (repressor) to switch off structural gene action

D) regulator protein to switch on gene action

Correct Answer: C

Solution :

Operator gene is a part of DNA between promotor and structural gene, where repressor binds to stop activity of RNA polymerase.