The eukaryotic cell cycle. Cells that are destined to divide progress through a series of stages, denoted G1, S, G2, and M phases (mitosis). This diagram shows the progression of a cell through mitosis to produce two daughter cells. The original diploid cell had two pairs of chromosomes, for a total of four individual chromosomes. During S phase, these have replicated to yield eight sister chromatids. After mitosis is complete, there are two daughter cells each containing four chromosomes.