Correct option is B
Correct Answer: (b)
Explanation: PCNA functions as a sliding clamp that encircles DNA and tethers DNA polymerase to the template strand during replication. This association prevents dissociation of the polymerase, thereby greatly increasing its processivity. PCNA is particularly important for efficient synthesis of the lagging strand. Hence, its primary role is to enhance DNA polymerase activity rather than catalyzing or unwinding reactions.
Information Booster
· PCNA is the eukaryotic homolog of the bacterial β-clamp.
· It forms a homotrimeric ring structure around double-stranded DNA.
· PCNA interacts with multiple proteins involved in DNA replication and repair.
· Clamp loading onto DNA requires the ATP-dependent replication factor C (RFC).
· High processivity is essential for rapid and accurate genome duplication.
Additional Knowledge
RNA primer synthesis is carried out by primase as part of the DNA polymerase α–primase complex, not by PCNA. Removal of RNA primers from Okazaki fragments is performed by RNase H and FEN1 nucleases. Unwinding of parental DNA is mediated by helicases, such as the MCM complex in eukaryotes. Thus, PCNA’s specialized role is confined to acting as a sliding clamp that stabilizes DNA polymerase on the DNA template.
