What role do single-strand binding proteins play during DNA replication?

What role do single-strand binding proteins play during DNA replication?

• A. They stabilize exposed single strands and prevent reannealing.
• B. They unwind the double helix to expose bases.
• C. They synthesize RNA primers.
• D. They ligate nicks in the sugar-phosphate backbone.

Answer: (A)

During DNA replication, the two strands are separated so each serves as a template. After the helicase unwinds the helix, single-strand binding proteins grab onto the exposed single-stranded DNA, keeping it from reannealing and from forming secondary structures. This stabilization is crucial for the DNA polymerases to efficiently copy the template, especially on the lagging strand where many short ssDNA segments appear. SSBs also protect the delicate ssDNA from nucleases. They don’t unwind DNA, synthesize RNA primers, or ligate backbone nicks—that role belongs to helicase, primase, and ligase, respectively.

During DNA replication, the two strands are separated so each serves as a template. After the helicase unwinds the helix, single-strand binding proteins grab onto the exposed single-stranded DNA, keeping it from reannealing and from forming secondary structures. This stabilization is crucial for the DNA polymerases to efficiently copy the template, especially on the lagging strand where many short ssDNA segments appear. SSBs also protect the delicate ssDNA from nucleases. They don’t unwind DNA, synthesize RNA primers, or ligate backbone nicks—that role belongs to helicase, primase, and ligase, respectively.