What is the role of DNA Polymerase in proofreading?

What is the role of DNA Polymerase in proofreading?

• A. It synthesizes RNA primers.
• B. It seals nicks in the sugar-phosphate backbone.
• C. It detects, removes, and replaces incorrectly paired nucleotides.
• D. It unwinds DNA ahead of replication.

Answer: (C)

Proofreading during DNA replication is carried out by DNA polymerase through its 3' to 5' exonuclease activity. When a nucleotide is mismatched, the enzyme detects the error, removes the incorrect nucleotide, and then resynthesizes the correct one, greatly increasing replication fidelity. This proofreading step happens before the rest of the strand is completed and works alongside later mismatch repair. Other processes mentioned are handled by different enzymes: primase makes RNA primers, DNA ligase seals nicks, and helicase unwinds the DNA helix ahead of the replication fork.

Proofreading during DNA replication is carried out by DNA polymerase through its 3' to 5' exonuclease activity. When a nucleotide is mismatched, the enzyme detects the error, removes the incorrect nucleotide, and then resynthesizes the correct one, greatly increasing replication fidelity. This proofreading step happens before the rest of the strand is completed and works alongside later mismatch repair. Other processes mentioned are handled by different enzymes: primase makes RNA primers, DNA ligase seals nicks, and helicase unwinds the DNA helix ahead of the replication fork.