The Cell Cycle "50 to 75 trillion cells" reside in a human (1). These cells are known as eukaryotes. During a eukaryote's lifespan, it will grow and divide in order to create new cells. This process eukaryotes undergo to reproduce cells is known as the cell cycle. The cell cycle is composed of three stages: growth, mitosis, and cytokinesis. |
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Growth Growth consists of three stages: interphase (G1 phase), S phase, and G2 phase. In interphase, the cell functions normally and continues to increase in size. In S phase, DNA copies each chromosome, producing two copies of each. Each copy is known as a sister chromatid. Finally, the cell prepares for division during G2 phase (2).  The image above shows the steps of growth within the cell cycle. |
Mitosis Prophase, metophase, anaphase, and telophase make up mitosis. In prophase, chromosomes become visible, shorter and thicker. The nuclear envelop breaks down as microtubules form and move to opposite sides of the cell. In metophase, the chromosomes line up along the cell's equator and spindles attach to each sister chromatid. In anaphase, the sister chromatids separate and move towards opposite ends of the cell. In telophase, the two groups of chromosomes reach the ends of the cell. While a new nuclear envelope starts to form around each group, the chromosomes uncoil and the spindle vanish (2). |
Cytokinesis The process in which the cytoplasm and organelles of a cell divide is called cytokinesis. This phase is also referred to as the C phase. The result of mitosis and cytokinesis is the formation of two genetically identical cells are formed once mitosis and cytokinesis are completed (2).  The photograph above shows a cell undergoing cytokinesis. Still Confused? |
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