Question

During DNA replication, what occurs at the origin of replication? A. The two strands that will make up a DNA double helix begin to chemically bind. B. The enzyme RNA polymerase starts to copy the DNA sequence of a chromosome. C. The enzyme helicase begins splitting apart the strands of a DNA molecule. D. A single strand of DNA starts to combine with a single strand of RNA.

Answer 1

Answer:

C

Explanation:

The origin of replication refers to the site at which DNA replication begins. The process of DNA replication - which occurs prior to cell division -  generates a new copy of the DNA.

DNA replication involves unwinding of the DNA double helix, creating a Y shape called the replication fork. The two strands are then replicated, and now there are two DNA molecules, each containing one "old" DNA strand and one "new" DNA strand.

The first stage at the origin of replication is that the enzyme helicase begins splitting apart the strands of a DNA molecule. (C)

The answer is not A, as the two DNA strands are already in the double helix. The answer is not B, as the enzyme responsible for copying the DNA sequence is DNA polymerase, not RNA polymerase. The answer also cannot be D, because although short RNA primers are involved in DNA replication, this does not occur at the origin of replication.