What is the chromosome and DNA molecule count in a cell at G2 phase, if it had 4 chromosomes in G1 phase?

During the G1 phase of the cell cycle, a cell contains a certain number of chromosomes, which are made up of single DNA molecules. In this specific scenario, if the cell starts with 4 chromosomes in G1, each of those chromosomes is single and contains one DNA molecule, leading to a total of 4 DNA molecules at that phase.

As the cell progresses to the G2 phase, it undergoes DNA replication during the S phase. This process involves the duplication of each chromosome, meaning that each original chromosome is copied, resulting in two sister chromatids for each one. Therefore, the total number of chromosomes remains the same (4) because the sister chromatids are still considered part of the same chromosome until cell division occurs. However, since each of these chromosomes has now been replicated, there are a total of 8 DNA molecules present in the G2 phase.

Thus, in the G2 phase, the correct assessment is that the cell has 4 chromosomes (each with two sister chromatids) but 8 DNA molecules as a result of the replication process that has taken place.