Question:
In DNA replication, which enzyme is responsible for unwinding the double helix and separating the DNA strands?
In DNA replication, which enzyme is responsible for unwinding the double helix and separating the DNA strands?
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In DNA replication, remember that helicase "unzips" the DNA by breaking hydrogen bonds, while other enzymes like DNA polymerase and ligase build and join the new strands.
Updated On: Jan 13, 2026
- DNA polymerase
- Helicase
- Ligase
- Primase
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The Correct Option is B
Solution and Explanation
DNA replication is the process by which a cell copies its DNA before cell division. The double-stranded DNA molecule must be unwound and separated to allow the replication machinery to access the template strands. This process is carried out by the enzyme helicase.
Helicase binds to the DNA at the replication fork and breaks the hydrogen bonds between the complementary base pairs, unwinding the double helix and separating the two strands into single strands. These single strands then serve as templates for the synthesis of new DNA strands.
The other enzymes listed have different roles in DNA replication:
- DNA polymerase: Synthesizes new DNA strands by adding nucleotides complementary to the template strand.
- Ligase: Joins Okazaki fragments on the lagging strand by forming phosphodiester bonds.
- Primase: Synthesizes short RNA primers that provide a starting point for DNA polymerase to begin synthesis.
Thus, the enzyme responsible for unwinding the double helix and separating the DNA strands is helicase.
Helicase binds to the DNA at the replication fork and breaks the hydrogen bonds between the complementary base pairs, unwinding the double helix and separating the two strands into single strands. These single strands then serve as templates for the synthesis of new DNA strands.
The other enzymes listed have different roles in DNA replication:
- DNA polymerase: Synthesizes new DNA strands by adding nucleotides complementary to the template strand.
- Ligase: Joins Okazaki fragments on the lagging strand by forming phosphodiester bonds.
- Primase: Synthesizes short RNA primers that provide a starting point for DNA polymerase to begin synthesis.
Thus, the enzyme responsible for unwinding the double helix and separating the DNA strands is helicase.
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