Mitosis

During mitosis, the sister chromatids are segregated into a pair of identical daughter nuclei (Figure 1).

• Prophase: During prophase, the sister chromatids are condensed. The centrosome outside of the nucleus will separate. The microtubule will form between the centrosomes (poles) to make the mitotic spindle.
• Prometaphase: The nuclear envelope breaks down. The spindle can now attach to the chromosomes via the kinetochore.
• Metaphase: The chromosomes are aligned at the equator. The kinetochore microtubule connects sister chromatids to opposite poles.
• Anaphase: The sister chromatids separate to form two daughter chromosomes, and each is pulled slowly toward two opposite poles.
• Telophase: The two sets of daughter chromosomes arrive at the poles and decondense. A new nuclear envelope begins to form around each set.

Mitosis results in two diploid cells. Diploid refers to cells, nuclei, or organisms containing two sets of chromosomes (2n). Mitosis is one of two cell division types. The other type of cell division is meiosis. Learn more about mitosis and meiosis comparison.

Figure 1. Phases of the cell cycle: diagram of the chromosomes (DNA), organelles and mitotic spindle in each stage of cell division.

Mitosis consists of five key stages, with interphase being the resting or growth stage. Briefly, during prophase the sister chromatids condense and a centrosome forms outside of the nucleus beginning to form the mitotic spindle. During prometaphase the nuclear envelope breaks down and the chromosomes can connect to the mitotic spindle. During metaphase the chromosomes align along the center of the cell with sister chromatids connected to opposite poles of the spindle. These chromatids are then separated to form distinct chromosomes as each is pulled towards the opposite pole. Finally, during telophase the chromosomes decondense and a new nuclear envelope begins to form.