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 B₁₂is the allosteric effector of the repressor -the molecule that binds to the repressor to affect its activity. Predict how vitamin B₁₂will influence repressor activity. A) When vitamin B₁₂binds to the repressor, the repressor binds to the operator. B) When vitamin B₁₂binds to the repressor, the repressor can bind to RNA polymerase. C) When vitamin B₁₂binds to the repressor, the repressor cannot bind to RNA polymerase. D) When vitamin B₁₂binds to the repressor, the repressor cannot bind to the operator.

Question

Quizplus · Accepted Answer

When an allosteric effector, such as vitamin B₁₂, binds to a repressor protein, it typically induces a conformational change that either activates or deactivates the repressor's ability to bind to the operator sequence. In this context, the effector binding to the repressor and causing it to bind to the operator suggests a classic negative feedback mechanism, where the presence of the end product (vitamin B₁₂) inhibits further production by activating the repressor.

Imagine That You Discover a Bacterial Operon Involved in the Synthesis