Which of the following processes would result from a mutation that deactivates a regulatory gene of a repressible operon in an E. coli cell?
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

A repressible operon is usually under negative control, meaning the operator is blocked by a repressor protein that binds to it. The regulatory gene codes for the repressor protein, so if this gene is mutated and no longer produces the repressor, then the operator is no longer blocked and transcription of the structural gene under control of the operon will continuously occur. Therefore, choice A is the correct answer.

Which of the Following Processes Would Result from a Mutation