Proofreading by DNA polymerase involves the removal of which of the following during DNA replication?

• A. RNA primers
• B. Phosphate groups from the DNA backbone
• C. Ribose sugars
• D. Incorrectly paired nucleotides

Answer: (D)

Verified step by step guidance

1. Understand the role of DNA polymerase during DNA replication, which is to synthesize a new strand of DNA complementary to the template strand.
2. Recognize that DNA polymerase has a proofreading function, which means it can identify and remove incorrectly paired nucleotides that were mistakenly incorporated during replication.
3. Recall that RNA primers are removed by a different enzyme called RNase H or DNA polymerase I in prokaryotes, not by the proofreading activity of DNA polymerase.
4. Note that phosphate groups and ribose sugars are structural components of the DNA backbone and are not removed during proofreading; the proofreading specifically targets mismatched bases.
5. Conclude that the proofreading activity of DNA polymerase involves the removal of incorrectly paired nucleotides to ensure high fidelity in DNA replication.