Imagine that you discover a bacterial operon involved in the synthesis of vitamin B₁₂.This operon is regulated by a repressor protein that binds to an operator sequence.Vitamin B₁₂ is the allosteric effector of the repressor-the molecule that binds to the repressor to affect its activity.Predict how vitamin B₁₂ will influence repressor activity.
A)When vitamin B₁₂ binds to the repressor,the repressor binds to the operator.
B)When vitamin B₁₂ binds to the repressor,the repressor cannot bind to the operator.
C)When vitamin B₁₂ binds to the repressor,the repressor can bind to RNA polymerase.
D)When vitamin B₁₂ binds to the repressor,the repressor cannot bind to RNA polymerase.

Question

Quizplus · Accepted Answer

Vitamin B₁₂ acts as an allosteric effector that enables the repressor to bind to the operator, thereby inhibiting the operon and preventing the synthesis of vitamin B₁₂ when it is abundant.

Imagine That You Discover a Bacterial Operon Involved in the Synthesis