If the enzyme helicase was denatured, which step in DNA replication would be most affected?

Question

If the enzyme helicase was denatured, which step in DNA replication would be most affected?

1. The removal of the RNA primers
2. The correct pairing of the nucleotides
3. The formation of the replication fork
4. The formation of the Okazaki fragments

Answer 1

1,2 and 4 would never be possible if helicase was denatured, as the DNA strands would never separate, so the question is very confusing but I would have to say 3, as there would never be a replication fork, and therefore no replication if the DNA strands aren't able to separate.

Answer 2

Helicase is meant to unwind and unzip the DNA by breaking the hydrogen bonds between the nitrogenous bases.

Let's look at the answer choices and pick them apart.

1. The removal of the RNA primers - primase is the enzyme that adds RNA primers (it's in the name! Primase adds primers!) However, the enzyme that *removes* the RNA primers is DNA polymerase I. (Think about it -- you can't have RNA in the final DNA strands).
2. The correct pairing of the nucleotides - this is the function of DNA polymerase III.
3. The formation of the replication fork - the replication fork is formed when the DNA strands are splitting. (Think about how a fork in the road is the area where the road splits) Since the helicase is splitting the DNA strands and "unzipping" the double helix, if helicase was not working, then the strands would not be splitting and there would be no replication fork. This is the correct answer.
4. The formation of the Okazaki fragments. Okazaki fragments are formed on the lagging strand by both primase adding RNA primers and DNA polymerase III adding new nucleotides.