A mutation that inactivates the regulatory gene of a repressible operon in an E. coli cell would result in
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) inactivation of RNA polymerase by alteration of its active site.
E) continuous translation of the mRNA because of alteration of its structure.

Question

Quizplus · Accepted Answer

The regulatory gene in a repressible operon codes for the repressor protein which inhibits the transcription of structural genes when a specific molecule is present in the cell. If the regulatory gene is mutated and becomes inactive, then the repressor protein will not be produced, leading to the continuous transcription of the structural gene controlled by that regulator.

A Mutation That Inactivates the Regulatory Gene of a Repressible