Primase

Definition

Primase is an enzyme involved in the synthesis of RNA primers during DNA replication. It provides a starting point for DNA polymerase to begin synthesizing the new DNA strand.

5 Must Know Facts For Your Next Test

1. Primase synthesizes short RNA sequences called primers that are complementary to a single-stranded DNA template.
2. The primers synthesized by primase are necessary because DNA polymerases can only add nucleotides to an existing strand of DNA.
3. Primase activity is crucial during the initiation phase of DNA replication on both the leading and lagging strands.
4. On the lagging strand, multiple RNA primers are needed as it is synthesized discontinuously in Okazaki fragments.
5. Primase is part of a larger protein complex known as the primosome.

Review Questions

• What role does primase play in DNA replication?
• Why are RNA primers necessary for DNA polymerases?
• How does primase function differently on the leading and lagging strands?

Related terms

DNA Polymerase:

An enzyme that synthesizes new strands of DNA complementary to the template strand.

Okazaki Fragments:

Short sequences of DNA nucleotides which are synthesized discontinuously and later linked together on the lagging strand.

Primosome: A protein complex that includes primase and other proteins essential for initiating DNA replication.