Which DNA replication enzyme unzips DNA to form replication fork?

• A. DNA polymerase
• B. Helicase
• C. Primase
• D. Ligase

Answer: (B)

Unzipping the DNA to form the replication fork is done by helicase. It uses energy from ATP to break the hydrogen bonds between base pairs, separating the two strands and creating the fork as the DNA opens for replication. This opening exposes the single-stranded templates that will be copied.

DNA polymerase then takes over to synthesize the new DNA by adding nucleotides in a 5' to 3' direction, starting from RNA primers provided by primase. Primase creates those RNA primers to give DNA polymerase a starting point. Finally, ligase seals the remaining nicks after the lagging strand is synthesized, joining Okazaki fragments into a continuous strand. Single-strand binding proteins help keep the unwound strands from reannealing, stabilizing the replication fork as work proceeds.