Which mechanism ensures accurate DNA replication?

• A. DNA replication occurs through random joining of nucleotides without a template.
• B. RNA acts as the template for DNA replication, with no proofreading.
• C. Complementary base pairing with DNA polymerase proofreading ensures accurate replication.
• D. Replication results in immediate protein production from DNA.

Answer: (C)

Accurate DNA replication relies on using the existing DNA strand as a template and enforcing correct base pairing. DNA polymerase adds nucleotides opposite the template according to base-pair rules (A pairs with T, G pairs with C) and uses a proofreading activity to remove any mispaired nucleotides. If a mismatch slips in, proofreading catches and corrects it before proceeding, which greatly reduces errors. This combination of template-directed synthesis and enzymatic proofreading is what keeps the copied DNA faithful. The idea that RNA serves as the full template with no proofreading, or that replication would occur without a template, would not produce a reliable copy, and immediate protein production from DNA describes transcription and translation, not replication.