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

• A. It removes RNA primers and replaces them with DNA nucleotides during Okazaki fragment processing.
• B. It synthesizes short RNA primers to provide a free $3^{\prime }$ $OH$ group for DNA synthesis to begin.
• C. It synthesizes new DNA by adding deoxyribonucleotides to the $3^{\prime }$ end of a growing strand using the template strand.
• D. It unwinds the DNA double helix ahead of the replication fork by breaking hydrogen bonds between base pairs.

Answer: (C)

Verified step by step guidance

1. Identify the role of DNA polymerase III in prokaryotic DNA replication by understanding the main enzymes involved and their specific functions.
2. Recall that DNA polymerase III is the primary enzyme responsible for synthesizing new DNA strands by adding nucleotides complementary to the template strand.
3. Note that DNA polymerase III adds nucleotides specifically to the 3\' hydroxyl (OH) end of the growing DNA strand, extending it in the 5\' to 3\' direction.
4. Distinguish DNA polymerase III's function from other enzymes: DNA polymerase I removes RNA primers, primase synthesizes RNA primers, and helicase unwinds the DNA helix.
5. Conclude that the primary function of DNA polymerase III is to synthesize new DNA by adding deoxyribonucleotides to the 3\' end of the growing strand using the template strand.