Question
The cell shown in the illustration has recently completed the syntheses phase (S phase)
of the cell cycle and is in prophase of mitosis. What happened in this cell during the S
phase in preparation for division? Describe evidence that supports your answer.
Answer
During the S phase, the cell replicated its DNA to prepare for cell division. This means that each chromosome now consists of two identical sister chromatids. Evidence to support this includes the presence of visible chromosomes in the prophase stage of mitosis, as well as the fact that each chromosome should have a corresponding sister chromatid.