The Lac Repressor Has Been Mutated So That Its Binding

question 73

Multiple Choice

The lac repressor has been mutated so that its binding site for the operator has been altered to the extent that it is unable to bind to the operator.What is the likely effect of this mutation on the lac operon?

• A) The repressor will be unable to bind to the operator; the operon will bind RNA polymerase and it will thus be turned on.
• B) The repressor will bind to the operator despite the mutation, and will suppress transcription of the operon in the presence and absence of lactose.
• C) The lac operon will be protected by the altered repressor.
• D) The repressor will be unable to bind to the operator; therefore, the ability of RNA polymerase to bind there will be severely hampered.

---

Definitions:

Latissimus Dorsi

A large, flat muscle on the back that helps in the movement of the shoulders and arms.

Trapezius Group

A collection of muscles extending from the neck to the mid-back, responsible for moving the shoulder blades and supporting the arm.

Rhomboideus Major

A muscle in the back that connects the spine to the scapula, involved in retracting the shoulder blade.

Infraspinatus

A muscle located on the back of the shoulder blade that is responsible for the external rotation of the shoulder joint.