Question

What would be the result of a mutation that deactivates the regulatory gene of a repressible operon in an escherichia coli cell?

A) irreversible binding of the repressor to the operator
B) continuous transcription of the structural gene controlled by that regulator
C) continuous translation of the mRNA because of alternation of its structure
D) complete inhibition of transcription of the structural gene controlled by that regulator

Answer 1

The correct answer is: B) continuous transcription of the structural gene controlled by that regulator

A regulatory gene is gene that encodes for a protein, such as a repressor (or activators) that controls the transcription of another gene or group of genes.

The regulatory gene of a repressible operon encodes for the repressor that inhibits gene transcription. So, when that repressor isn’t active, transcription occurs continuously.