In DNA replication, what is the primary function of DNA polymerase?

• A. To synthesize a new DNA strand by adding complementary nucleotides to the $3^{\prime }$ end of a primer
• B. To unwind the DNA double helix by breaking hydrogen bonds between base pairs
• C. To join Okazaki fragments by forming phosphodiester bonds between them
• D. To synthesize short RNA primers to initiate DNA synthesis

Answer: (A)

Verified step by step guidance

1. Understand the role of DNA polymerase in DNA replication, which involves synthesizing new DNA strands.
2. Recall that DNA polymerase adds nucleotides complementary to the template strand, ensuring accurate base pairing (A with T, and G with C).
3. Recognize that DNA polymerase can only add nucleotides to the 3\' end of an existing strand or primer, meaning DNA synthesis occurs in the 5\' to 3\' direction.
4. Differentiate DNA polymerase's function from other enzymes involved in replication, such as helicase (which unwinds the DNA), ligase (which joins Okazaki fragments), and primase (which synthesizes RNA primers).
5. Conclude that the primary function of DNA polymerase is to synthesize a new DNA strand by adding complementary nucleotides to the 3\' end of a primer.