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Transcript
Mitosis is a process of nuclear division which produces two genetically identical daughter cells. It takes place in 5 stages; prophase, metaphase, anaphase, telophase and cytokinesis Nuclear envelope begins to disintegrate In prophase, chromosomes shorten and thicken (supercoil) and become visible under a light microscope. Each consist of a pair of sister chromatids. The nuclear envelope breaks down and disappears. The centriole divides and the two daughter centrioles move to the cell poles and form the spindle. Centrioles begin to move to the poles of the cell DNA wraps around histone proteins to form condensed, X-shaped, chromosomes Centrioles are at the poles of the cell In metaphase, the chromosomes move to the central region of the spindle, the equator, and each becomes attached to a spindle thread by its centromere. A protein spindle grows from the centrioles and attaches to the chromosomes at the centromere Chromosomes are lined up along the equator of the cell Centromeres split Spindles contract and shorten In anaphase, the replicated sister chromatids which make up the chromosome are Sister separated form each other as chromatids the centromere splits. The are pulled spindle fibres shorten, pulling towards opposite poles the sister chromatids further of the cell away from each other towards the poles. Nuclear envelope reforms around the ‘new’ nuclei In cytokinesis, the cytoplasm divides in two, forming two identical daughter cells. Each cell has the exact same genetic information, and so is capable of doing everything that the parent cell could do. The cell then returns to interphase. In telophase, the separated sister chromatids, which are now chromosomes, reach the poles of the cell. A new nuclear envelope forms around each, and the spindle breaks down and disappears. The chromosomes uncoil and decondense to reform chromatin.