Question

During DNA replication, after adding each nucleotide to a new strand of DNA, DNA polymerase checks that the nucleotide it just added is the correct one, i.e. that it is complementary to the opposite nucleotide on the template strand. This activity is called the ____________ activity of DNA polymerase. If this activity detects that a wrong nucleotide has been added, then the _____________ activity of DNA polymerase is activated, allowing the wrong nucleotide to be removed.

Answer 1

a) proofreading.

b) exonuclease.

As DNA is the genetic material, at the time of DNA replication, if any error get incorporated in any of the growing strand it will inherit in the progenies as a mutation. If in every round of replication, wrong nucleotide is incorporated in the newly synthesized strand then the genetic stability of that organism will be compromised. To avoid this kind of situation, organism has developed a strategy called proofreading, in which they identify the wrongly incorpotared nucleotide by their base pairing patterns. If any wrong base is identified, then by the exonuclease enzymes the wrongly incorpotared bases are excluded out from the newly synthesized strands.