True or False: Primase can start an RNA primer from scratch.

True or False: Primase can start an RNA primer from scratch.

• A. False
• B. It requires a pre-existing primer to begin synthesis
• C. True
• D. It synthesizes DNA

Answer: (C)

Primase can start an RNA primer de novo, meaning it can begin RNA synthesis from scratch without a pre-existing primer. At the replication fork, it uses the DNA template to lay down a short RNA primer, providing the 3' hydroxyl needed for DNA polymerases to begin extending DNA. In bacteria, DNA polymerase III extends this Primer after primase lays it down; in eukaryotes, the primase is part of a complex with DNA polymerase α that first makes a short RNA primer and then a brief DNA segment, after which the RNA is removed and replaced by DNA by other polymerases. So the statement is true because primase is specialized to initiate RNA synthesis without a pre-existing primer.

Primase can start an RNA primer de novo, meaning it can begin RNA synthesis from scratch without a pre-existing primer. At the replication fork, it uses the DNA template to lay down a short RNA primer, providing the 3' hydroxyl needed for DNA polymerases to begin extending DNA. In bacteria, DNA polymerase III extends this Primer after primase lays it down; in eukaryotes, the primase is part of a complex with DNA polymerase α that first makes a short RNA primer and then a brief DNA segment, after which the RNA is removed and replaced by DNA by other polymerases. So the statement is true because primase is specialized to initiate RNA synthesis without a pre-existing primer.