Which statement describes the function of helicase during DNA replication?

Which statement describes the function of helicase during DNA replication?

• A. It seals nicks in the sugar-phosphate backbone.
• B. It synthesizes the leading strand.
• C. It prims RNA primers.
• D. It unwinds the double helix to separate strands.

Answer: (D)

Helicase is responsible for unwinding the DNA double helix to separate the two strands, which is the first essential step in replication. By breaking the hydrogen bonds between base pairs, it creates the replication fork and exposes single-stranded templates that new polymer strands can copy. This unwinding is powered by ATP, and once the strands are separated, other proteins stabilize them and DNA polymerases can synthesize new DNA. The other described roles don’t fit helicase: sealing nicks in the backbone is done by DNA ligase; priming RNA primers is the job of primase; synthesizing the new leading strand is carried out by DNA polymerase after the template is exposed.

Helicase is responsible for unwinding the DNA double helix to separate the two strands, which is the first essential step in replication. By breaking the hydrogen bonds between base pairs, it creates the replication fork and exposes single-stranded templates that new polymer strands can copy. This unwinding is powered by ATP, and once the strands are separated, other proteins stabilize them and DNA polymerases can synthesize new DNA.

The other described roles don’t fit helicase: sealing nicks in the backbone is done by DNA ligase; priming RNA primers is the job of primase; synthesizing the new leading strand is carried out by DNA polymerase after the template is exposed.