During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following, EXCEPT
A) a site for the entry of ribonucleoside triphosphates.
B) a site for the exit of the diphosphates removed from the nucleotide triphosphates.
C) a site for the growing RNA strand.
D) a site for the double- stranded DNA molecule.

Question

Quizplus · Accepted Answer

During elongation by RNA polymerase, there are indeed three prominent channels: one for the entry of ribonucleoside triphosphates (NTPs), one for the growing RNA strand, and one for the double-stranded DNA template. However, there is no specific channel dedicated for the exit of diphosphates (the by-products of NTP incorporation into the RNA strand); these molecules typically diffuse away from the enzyme.

During Elongation, RNA Polymerase Has Three Prominent Channels, or Grooves