At which stage of the cell cycle does a cell contain twice its normal number of chromosomes?

During the cell cycle, the stage in which a cell contains twice its normal number of chromosomes occurs after DNA replication has taken place. This replication happens during the S phase (Synthesis phase) of interphase, before the cell enters mitosis.

In mitosis, specifically during prophase, metaphase, anaphase, and telophase, chromosomes are organized and separated for distribution to the daughter cells. At prophase, chromosomes are condensed and visible, but it’s during anaphase that the replicated chromosomes, which are called sister chromatids, are pulled apart towards opposite poles of the cell.

Initially, each chromosome is duplicated during the S phase, resulting in two identical sister chromatids for each chromosome. At the point of anaphase, the chromatids are separated, but before this separation occurs, the cell indeed contains double the amount of chromosomes, as each chromosome exists as two sister chromatids. This makes anaphase the critical phase where the understanding of chromosome number and distribution is essential, highlighting how the cell transitions from having double the number of chromosomes to distributed single chromatids moving toward the poles.

Ultimately, by the end of mitosis, during telophase, the chromosomes will have arrived at each pole and begin to