Why is proofreading by DNA Polymerase important?

Why is proofreading by DNA Polymerase important?

• A. It Speeds Up Replication
• B. It Removes Mismatched Bases After Replication
• C. It Ensures the Proper Complementary Base Is Added, Maintaining Genetic Fidelity
• D. It Binds to RNA Primers

Answer: (C)

Proofreading by DNA polymerase is about preserving genetic fidelity during replication. As the enzyme adds nucleotides, it also checks that each new base pairs correctly with the template strand. If a mismatch slips in, the polymerase uses a separate exonuclease activity to remove the incorrect nucleotide and then resumes synthesis with the correct one. This immediate correction keeps the newly formed DNA accurately matched to the template, dramatically reducing the number of mutations passed on to daughter cells. It’s not primarily about speeding up replication—proofreading can even slow synthesis a bit because of the additional check and correction steps. It also isn’t a postreplication cleanup, which is handled by other repair systems, nor is it about binding RNA primers (that’s the role of primase).

Proofreading by DNA polymerase is about preserving genetic fidelity during replication. As the enzyme adds nucleotides, it also checks that each new base pairs correctly with the template strand. If a mismatch slips in, the polymerase uses a separate exonuclease activity to remove the incorrect nucleotide and then resumes synthesis with the correct one. This immediate correction keeps the newly formed DNA accurately matched to the template, dramatically reducing the number of mutations passed on to daughter cells. It’s not primarily about speeding up replication—proofreading can even slow synthesis a bit because of the additional check and correction steps. It also isn’t a postreplication cleanup, which is handled by other repair systems, nor is it about binding RNA primers (that’s the role of primase).