Consider a cell in which one of the proteins or enzymes involved in DNA replicat

Question

Consider a cell in which one of the proteins or enzymes involved in DNA replication is altered in a way that results in an increased rate of single-base changes in the newly synthesized DNA strand. Which function of which protein is MOST likely disrupted in this situation?

1. the unwinding function of helicase

2.the winding stress relief function of topoisomerase II

3.the fragment joining function of DNA ligase

4.the proofreading function of DNA polymerase

5.the strand separation function of single-stranded binding protein

10. Why is primase required for replication?

1.DNA polymerases cannot begin without a primer containing a free 3 '-OH.

2.DNA polymerases can only begin synthesis if they are stimulated by dimerization with a primase subunit.

3.Primase recruits helicase to the site of DNA synthesis.

4. Primase is required for proofreading DNA during replication.

Explanation / Answer

Answer:

9. (4) the proofreading function of DNA polymerase

Explanation:

During DNA synthesis, most DNA polymerases "check their work," fixing the majority of mispaired bases in a process called proofreading. Immediately after DNA synthesis, any remaining mispaired bases can be detected and replaced in a process called mismatch repair.

If repair function is disrupted, then there would be increased single-base changes following replication of DNA.

10. (1) DNA polymerases cannot begin without a primer containing a free 3 '-OH.

Explanation:

It is critical that primers are synthesized by primase before DNA replication can occur. This is because the enzymes that synthesize DNA, which are called DNA polymerases, can only attach new DNA nucleotides to an existing strand of nucleotides. Therefore, primase serves to prime and lay a foundation for DNA synthesis.

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