Repressor proteins
A) prevent binding of RNA polymerase to DNA.
B) cause the DNA regions that contain the operator to twist or loop.
C) inactivate operon genes when their products are not required.
D) bind to sets of operators.
E) do all of these.

Question

Quizplus · Accepted Answer

Repressor proteins can prevent binding of RNA polymerase to DNA by physically blocking the polymerase's access to the promoter region. They can also cause the DNA regions that contain the operator to twist or loop, which can physically block the polymerase from transcribing the genes. Additionally, repressor proteins can bind to sets of operators and inactivate operon genes when their products are not required. Therefore, all of the choices represent correct functions of repressor proteins.

Repressor Proteins