After helicase unzips DNA during replication, which proteins attach to keep the strands separated?

After helicase unzips DNA during replication, which proteins attach to keep the strands separated?

• A. Single-strand binding proteins
• B. DNA polymerases
• C. Histones
• D. Ligases

Answer: (A)

When helicase unwinds the DNA, the two exposed single strands tend to re-anneal or form secondary structures, which would block replication. Single-strand binding proteins latch onto the exposed DNA strands, stabilizing them and preventing base pairing between the strands. This keeps the strands separated and accessible for the replication machinery to copy the DNA. They also help protect the exposed template and assist in coordinating other replication proteins. The other enzymes listed have different roles: DNA polymerases synthesize new DNA, histones package DNA into chromatin, and ligases seal Okazaki fragment nicks—none of these primarily function to keep the strands separated after unwinding.

When helicase unwinds the DNA, the two exposed single strands tend to re-anneal or form secondary structures, which would block replication. Single-strand binding proteins latch onto the exposed DNA strands, stabilizing them and preventing base pairing between the strands. This keeps the strands separated and accessible for the replication machinery to copy the DNA. They also help protect the exposed template and assist in coordinating other replication proteins. The other enzymes listed have different roles: DNA polymerases synthesize new DNA, histones package DNA into chromatin, and ligases seal Okazaki fragment nicks—none of these primarily function to keep the strands separated after unwinding.