What is the role of DNA helicase in DNA replication and DNA transcription?
BIOLOGY
SAT 2021
What is the role of DNA helicase in DNA replication and DNA transcription?
- A. DNA helicase replaces the RNA primers with DNA nucleotides in DNA replication. Helicase has no use in DNA transcription.
- B. DNA helicase disrupts the hydrogen bonding between the two strands of DNA and exposes the insides of the DNA helix, allowing for other enzymes to replicate or transcribe the single-stranded DNA.
- C. None of these
- D. DNA helicase relieves the torsional strain and supercoiling that DNA undergoes during replication/transcription, and in doing so helps maintain the DNA double helix.
Correct Answer: B. DNA helicase disrupts the hydrogen bonding between the two strands of DNA and exposes the insides of the DNA helix, allowing for other enzymes to replicate or transcribe the single-stranded DNA.
Explanation
DNA helicase is an enzyme that is able to slip between the two strands of DNA and disrupt the hydrogen bonds that keep the DNA in the double helix structure. This disruption opens up the DNA helix, and exposes sections of DNA that can then be transcribed or replicated. As helicase moves down the double helix, the DNA reforms into a double helix since the enzyme is no longer blocking the hydrogen bonds.
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