What is the chromosome composition of daughter cells after cytokinesis, given the starting cell had 4 chromosomes in G1 phase?

To understand the chromosome composition of daughter cells after cytokinesis, it’s important to consider the phases of the cell cycle and the events that occur during mitosis.

In the G1 phase, a cell with 4 chromosomes contains 4 DNA molecules because each chromosome consists of a single DNA molecule. As the cell progresses through the cell cycle, it enters the S phase, during which DNA replication occurs. By the end of the S phase, the 4 chromosomes have been duplicated, resulting in 8 DNA molecules. At this point, each chromosome consists of two identical sister chromatids.

When the cell completes mitosis, it divides into two daughter cells. Each daughter cell will receive one copy of each chromosome, meaning that they will each have 4 chromosomes, but they only contain a single DNA molecule per chromosome at this point since the sister chromatids are separated during anaphase.

Therefore, after cytokinesis, the chromosome composition for each daughter cell is 4 chromosomes, leading to a total of 4 DNA molecules, since all the sister chromatids have been separated and are considered independent chromosomes. This aligns with the correct answer.