The lac repressor has been mutated so that its binding site for lactose has been altered to the extent that it is unable to bind to lactose.What is the likely effect of this mutation on the lac operon?
A) The repressor will be unable to bind to the operator, and the operon will thus be turned on.
B) The repressor will bind to the operator and suppress transcription of the operon despite the presence of lactose.
C) The lac operon will be degraded by the altered repressor.
D) The repressor will bind to the operator and enhance the ability of RNA polymerase to bind there.

Question

Quizplus · Accepted Answer

The mutation prevents the repressor from binding lactose, so it remains bound to the operator, blocking transcription even when lactose is present.

The Lac Repressor Has Been Mutated So That Its Binding