Which function best describes proofreading by DNA polymerase?

Which function best describes proofreading by DNA polymerase?

• A. Genetic Fidelity by Ensuring Proper Base Pairing
• B. Increases Replication Speed
• C. Unwinds DNA
• D. Creates RNA Primers

Answer: (A)

Proofreading by DNA polymerase is all about maintaining accuracy during DNA replication. As the polymerase adds a nucleotide, it checks whether the pair fits correctly with the template. If a mismatch slips in, the enzyme’s 3' to 5' exonuclease activity removes the wrong nucleotide, and then synthesis resumes with the correct one. This proofreading step greatly increases genetic fidelity, keeping mutation rates low across generations. It doesn’t speed up replication—the process may pause briefly to fix mistakes, and the actions responsible for unwinding DNA or making RNA primers are handled by other enzymes (helicase unwinds the helix, primase lays down RNA primers). So the best description is that proofreading ensures proper base pairing to preserve genome integrity.

Proofreading by DNA polymerase is all about maintaining accuracy during DNA replication. As the polymerase adds a nucleotide, it checks whether the pair fits correctly with the template. If a mismatch slips in, the enzyme’s 3' to 5' exonuclease activity removes the wrong nucleotide, and then synthesis resumes with the correct one. This proofreading step greatly increases genetic fidelity, keeping mutation rates low across generations. It doesn’t speed up replication—the process may pause briefly to fix mistakes, and the actions responsible for unwinding DNA or making RNA primers are handled by other enzymes (helicase unwinds the helix, primase lays down RNA primers). So the best description is that proofreading ensures proper base pairing to preserve genome integrity.