Leading strand

Definition

The leading strand is a continuous DNA strand synthesized in the 5' to 3' direction during DNA replication. It is built toward the replication fork by DNA polymerase.

5 Must Know Facts For Your Next Test

1. The leading strand synthesis occurs continuously because it follows the opening of the replication fork.
2. DNA polymerase III is primarily responsible for synthesizing the leading strand in prokaryotes.
3. Single-strand binding proteins stabilize the leading strand to prevent re-annealing.
4. The leading strand requires only one RNA primer for initiation of synthesis.
5. The helicase enzyme unwinds the DNA helix ahead of the leading strand.

Review Questions

• What direction does synthesis of the leading strand occur in?
• Which enzyme is primarily responsible for synthesizing the leading strand in prokaryotes?
• Why does the leading strand require only one RNA primer?

Related terms

Lagging Strand:

A discontinuous DNA strand synthesized in short fragments called Okazaki fragments, away from the replication fork.

DNA Polymerase III: An enzyme that synthesizes new strands of DNA using a template strand, specifically involved in extending both leading and lagging strands.

Replication Fork:

A Y-shaped region where new DNA strands are synthesized and where both leading and lagging strands form.