Question

What part of the DNA replication process would be most directly affected if single-strand binding protein were not present?

(a) initiation of DNA synthesis
(b) Okazaki fragment synthesis
(c) leading-strand elongation
(d) lagging-strand completion

Answer 1

Without single-strand binding proteins, the stabilization of unwound DNA is directly affected, impairing lagging-strand completion during DNA replication by destabilizing Okazaki fragments.

Step-by-step explanation:

If single-strand binding proteins were not present, the DNA replication process that would be most directly affected is the stabilization of unwound DNA, which is essential for both the leading and lagging-strand completion. These proteins bind to and stabilize single-stranded DNA, preventing it from re-annealing or forming secondary structures, which could hinder the replication process. During replication, DNA polymerase III extends the new DNA from the RNA primer, and without single-strand binding proteins, the unwound DNA might re-anneal or become damaged, impeding DNA polymerase action on both the leading and lagging strands.

Specifically looking at the options given, choice (d) lagging-strand completion would be most directly affected because these proteins play a critical role in stabilizing the single-stranded DNA that forms the lagging strand's Okazaki fragments. On the lagging strand, DNA is synthesized discontinuously as Okazaki fragments, and the single-strand binding proteins are essential in maintaining the stability of these fragments until they can be linked together.