What is the role of primase in DNA replication?

Primase plays a crucial role in DNA replication by synthesizing RNA primers. During the replication process, the DNA double helix must be unwound, and the resulting single-stranded DNA cannot start the synthesis of a new strand on its own. This is where primase comes into play. It synthesizes short segments of RNA nucleotides, which serve as primers, providing a free 3' hydroxyl group for DNA polymerase to extend and synthesize the new DNA strand.

This RNA primer is essential because DNA polymerases require a primer to initiate DNA synthesis; they cannot start a new strand from scratch. Therefore, the action of primase is a critical first step in creating the new DNA strand, allowing for efficient replication of both the leading and lagging strands. Once the primers are laid down, the DNA polymerase can continue the process of elongation and complete the replication of the DNA molecule.