Question

Refer to Animation: Proofreading in DNA Replication. What is the name for the enzyme activity that DNA polymerase has when it removes an improperly paired base from the end of the growing strand?

Answer 1

Answer: Though the animation is not provided, proofreading in DNA replication is done by the 3'->5' exonuclease activity of DNA polymerase.

Explanation: Proofreading is a process by which the 3'->5' exonuclease activity of DNA polymerase double-checks each nucleotide after it is added and removes the mismatched nucleotide.

When a wrong nucleotide is added during replication, translocation of the DNA polymerase to the position where the next nucleotide is to be added is inhibited until the 3'->5' exonuclease activity of DNA polymerase double-checks and removes the incorrectly paired nucleotide so that the polymerase can begin replication again.