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During dna replication, what two processes must occur before the two strands of a dna molecule can separate?

User Midu
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2 Answers

1 vote

Final answer:

Before DNA strands can separate during replication, helicase unwinds the double helix and topoisomerase relieves supercoiling tension. Single-stranded binding proteins bind to the unwound strands to keep them separate and protected.

Step-by-step explanation:

During DNA replication, before the two strands of the DNA molecule can separate, two critical processes must occur. Helicase plays a major role in the first stage, which is the initiation phase. Helicase is responsible for unwinding the double helix structure of DNA. It separates the DNA strands at the origin of replication by breaking the hydrogen bonds between the nucleotide base pairs, akin to the unzipping of a zipper.

Concurrently, another enzyme, topoisomerase, acts ahead of the replication fork to prevent the DNA from becoming too tightly wound as it is unzipped by helicase. Topoisomerase breaks and subsequently rejoins the DNA phosphate backbone, thus relieving the supercoiled tension that the unwinding process might cause.

Additionally, single-stranded binding proteins (SSBs) coat the separate strands to prevent them from reannealing prematurely and to protect the single-stranded DNA from degradation, ensuring that each strand can serve effectively as a template for the creation of the new complementary strand.

User Ashtonian
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6 votes
The hydrogen bonds between the nitrogen bases must be broken, and the molecule must unwind.

Hope this helps! :)
User Pumpkinpro
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