Which enzyme unzips DNA by breaking hydrogen bonds to separate the complementary bases during replication?

Which enzyme unzips DNA by breaking hydrogen bonds to separate the complementary bases during replication?

• A. Topoisomerase
• B. Ligase
• C. Helicase
• D. Primase

Answer: (C)

Helicase unwinds the DNA by breaking the hydrogen bonds between base pairs, separating the two strands to create a replication fork. This energy-driven opening exposes each template strand so DNA polymerases can copy them. Without this unwinding step, synthesis cannot begin because polymerases need a single-stranded template. Other enzymes have different tasks: topoisomerase relieves the twisting that occurs when the helix is opened, ligase seals nicks in the sugar-phosphate backbone after fragments are synthesized, and primase lays down RNA primers so DNA polymerase has a starting point for synthesis.

Helicase unwinds the DNA by breaking the hydrogen bonds between base pairs, separating the two strands to create a replication fork. This energy-driven opening exposes each template strand so DNA polymerases can copy them. Without this unwinding step, synthesis cannot begin because polymerases need a single-stranded template. Other enzymes have different tasks: topoisomerase relieves the twisting that occurs when the helix is opened, ligase seals nicks in the sugar-phosphate backbone after fragments are synthesized, and primase lays down RNA primers so DNA polymerase has a starting point for synthesis.