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Multiple Choice
Which of the following proteins prevents unwound DNA from re-annealing into a double-stranded DNA molecule during replication?
A
DNA polymerase
B
DNA helicase
C
Single-strand binding proteins (SSBs)
D
Topoisomerase
Verified step by step guidance
1
Understand the context of DNA replication: During DNA replication, the double-stranded DNA must be unwound to allow each strand to be copied. This process involves several proteins that play specific roles.
Identify the role of DNA helicase: DNA helicase is responsible for unwinding the double-stranded DNA by breaking the hydrogen bonds between the base pairs, creating two single strands.
Consider the function of single-strand binding proteins (SSBs): Once the DNA is unwound, single-strand binding proteins bind to the separated strands to prevent them from re-annealing or forming secondary structures.
Differentiate the roles of other proteins: DNA polymerase synthesizes new DNA strands by adding nucleotides complementary to the template strand, while topoisomerase relieves the tension created by the unwinding process.
Conclude the specific role of SSBs: Single-strand binding proteins are crucial in maintaining the stability of the unwound DNA strands, ensuring they remain single-stranded and accessible for replication.