If a mutation deactivated a regulatory gene of a repressible operon in an E. coli cell which of the following describes the most likely outcome?
A) continuous transcription of the structural gene controlled by that regulator
B) complete inhibition of transcription of the structural gene controlled by that regulator
C) irreversible binding of the repressor to the operator
D) continuous translation of the mRNA because of alteration of its structure

Question

Quizplus · Accepted Answer

In a repressible operon, the regulatory gene typically codes for a repressor protein that can bind to the operator region and inhibit transcription of the structural genes when a specific corepressor is present. If a mutation deactivates this regulatory gene, the repressor protein would not be produced, leading to continuous transcription of the structural genes because there is nothing to inhibit their transcription.

If a Mutation Deactivated a Regulatory Gene of a Repressible