In the following schematic drawing, a transcribing RNA polymerase is moving toward the right on the DNA template as indicated. If the polymerase is allowed to rotate freely while the DNA is kept from doing so, would the enzyme rotate in a right-handed (R) or left-handed (L) fashion around the template? Write down R or L as your answer.

Question

In the following schematic drawing, a transcribing RNA polymerase is moving toward the right on the DNA template as indicated. If the polymerase is allowed to rotate freely while the DNA is kept from doing so, would the enzyme rotate in a right-handed (R) or left-handed (L) fashion around the template? Write down R or L as your answer.
In the following schematic drawing, a transcribing RNA polymerase is moving toward the right on the DNA template as indicated. If the polymerase is allowed to rotate freely while the DNA is kept from doing so, would the enzyme rotate in a right-handed (R) or left-handed (L) fashion around the template? Write down R or L as your answer.

Quizplus · Accepted Answer

When the polymerase is moving to the right, it induces positive supercoiling which hinders helix opening. If the enzyme is allowed to rotate freely (which is normally not the case in vivo), right-handed rotation will eliminate the superhelical tension, as if the polymerase is twisting to follow along the right-handed double helix.

In the Following Schematic Drawing, a Transcribing RNA Polymerase Is