Choose the correct answer from each of the four options given below:
Replication of DNA in the cell cycle occurs during the:
Topic: S phase of the cell cycle
Try it
Pick an option and check your answer. The full worked answer is below either way.
Answer
(c) S – Phase.
DNA is replicated during the S (SYNTHESIS) PHASE of interphase. Each chromosome is copied, so that it then consists of two identical chromatids joined at the centromere.
The name itself is the clue: the S phase is called the SYNTHESIS phase precisely because of DNA synthesis.
The three stages of interphase: G1 — the cell grows; RNA and proteins are made S — DNA is REPLICATED G2 — further growth and preparation for division
WHY IT MUST HAPPEN FIRST: mitosis separates the two chromatids into two daughter cells. Unless the DNA has already been copied there would be nothing to separate, and each daughter would receive only half the genetic material.
Option (b) ANAPHASE is the trap — it is a stage of MITOSIS, not of interphase, and it is when the copies are pulled APART, long after they were made.
S – Phase.