How Fast Does a Bacterial Ribosome Move on an MRNA

Question

How fast does a bacterial ribosome move on an mRNA?
A) At about 2 nucleotides per second, significantly lower than the speed of the RNA polymerase.
B) At about 5 nucleotides per second, comparable to the speed of the RNA polymerase.
C) At about 10 nucleotides per second, significantly lower than the speed of the RNA polymerase.
D) At about 20 nucleotides per second, comparable to the speed of the RNA polymerase.
E) At about 60 nucleotides per second, comparable to the speed of the RNA polymerase.

Accepted Answer

The polypeptide chain grows on the ribosome by about 20 amino acids per second, which is equivalent to an mRNA translocation rate of 60 nucleotides per second. This is comparable to the rate of transcription by the bacterial RNA polymerase (about 50 nucleotides per second). Indeed, a bacterial ribosome can translate mRNAs co-transcriptionally, by closely following an RNA polymerase and translating the same mRNA molecule that is being produced by the polymerase.