Question

Proofreading activity of DNA polymerase improves fidelity of replication by a factor of _____ fold.

1) 10-100
2) 1000-5000
3) 100-500
4) Does not improve it at all.

Answer 1

Proofreading activity of DNA polymerase improves the fidelity of DNA replication by 100-500 fold due to its ability to correct mismatches through exonuclease activity, which erases incorrect nucleotides before the correct ones are added.

Step-by-step explanation:

The proofreading activity of DNA polymerase greatly enhances the fidelity of DNA replication. This intrinsic mechanism allows the enzyme to correct many of the mistakes that occur during the replication process. DNA polymerase has the ability to sense a mismatched base pair as it adds nucleotides to the growing DNA strand. If a mismatch is detected, the enzyme will slow down and catalyze repeated hydrolyses of nucleotides until it reaches the mismatched base pair. This is primarily due to the 3' exonuclease activity of DNA polymerase, particularly DNA polymerase III, which performs proofreading. Due to this error correction capability, the proofreading activity of DNA polymerase improves the fidelity of replication by a factor of 100-500 fold, which is incredibly significant for maintaining the genetic integrity of organisms.