What is the role of RFC in DNA replication?

• A. RFC polymerizes nucleotides directly.
• B. RFC seals Okazaki fragments.
• C. RFC is the helicase that unwinds DNA.
• D. RFC (replication factor C) is the clamp loader that loads PCNA onto DNA in an ATP-dependent manner, enabling processive synthesis.

Answer: (D)

The main idea here is how replication proteins keep DNA polymerases working smoothly. Replication Factor C is the clamp loader that opens the PCNA sliding clamp and places it around primed DNA using ATP hydrolysis. Once PCNA is loaded, the polymerases (like Pol δ and Pol ε) can grip the DNA tightly and synthesize long stretches without falling off, which is essential for fast, processive replication of the genome. On the lagging strand, PCNA helps with rapid synthesis of Okazaki fragments by keeping the polymerase attached as each fragment is started and extended. So RFC’s job is to load PCNA onto DNA in an ATP-dependent manner, enabling those highly processive rounds of DNA synthesis.

RFC does not polymerize nucleotides—that’s the job of DNA polymerases. It does not seal Okazaki fragments—that’s done by DNA ligase. It does not unwind DNA—that’s the helicase’s role.