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Mitosis

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In cell biology, '''mitosis''' is a part of the cell cycle when replicated chromosomes are separated into two new nuclei. Cell division gives rise to genetically identical cells in which the number of chromosomes is maintained.<ref>{{REFweb |url=https://www.britannica.com/science/cell-biology/Cell-division-and-growth |title=Cell division and growth |website=britannica.com |publisher=ENCYCLOPÆDIA BRITANNICA }}</ref> In general, mitosis (division of the nucleus) is preceded by the S stage of interphase (during which the DNA is replicated) and is often accompanied or followed by cytokinesis, which divides the cytoplasm, organelles and cell membrane into two new cells containing roughly equal shares of these cellular components.<ref>{{REFweb |last= Carter |first= J. Stein |date= 2014-01-14 |title= Mitosis |url= http://biology.clc.uc.edu/courses/bio104/mitosis.htm |website= biology.clc.uc.edu |url-status= live |archive-url= https://web.archive.org/web/20121027084115/http://biology.clc.uc.edu/courses/bio104/mitosis.htm |archive-date= 2012-10-27 }}</ref> Mitosis and cytokinesis together define the '''mitotic''' ('''M''') '''phase''' of an animal cell cycle—the [[cell division|division]] of the mother cell into two daughter cells genetically identical to each other.

The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. During mitosis, the chromosomes, which have already duplicated, condense and attach to spindle fibers that pull one copy of each chromosome to opposite sides of the cell.<ref>{{REFweb|title = Cell Division: Stages of Mitosis {{!}} Learn Science at Scitable|url = http://www.nature.com/scitable/topicpage/mitosis-and-cell-division-205#|website = www.nature.com|access-date = 2015-11-16|url-status = live|archive-url = https://web.archive.org/web/20151114201118/http://www.nature.com/scitable/topicpage/mitosis-and-cell-division-205|archive-date = 2015-11-14}}</ref> The result is two genetically identical daughter nuclei. The rest of the cell may then continue to divide by cytokinesis to produce two daughter cells.<REF name=Maton1997/> Producing three or more daughter cells instead of the normal two is a mitotic error called tripolar mitosis or multipolar mitosis (direct cell triplication / multiplication).<ref name="Occurrence 2014">{{REFjournal | vauthors = Kalatova B, Jesenska R, Hlinka D, Dudas M | title = Tripolar mitosis in human cells and embryos: occurrence, pathophysiology and medical implications | journal = Acta Histochemica | volume = 117 | issue = 1 | pages = 111–25 | date =2015-01-01 | pmid =25554607 | doi =10.1016/j.acthis.2014.11.009 }}</ref> Other errors during mitosis can induce apoptosis (programmed cell death) or cause mutations. Certain types of cancer can arise from such mutations.<ref>{{REFjournal | vauthors = Kops GJ, Weaver BA, Cleveland DW | title = On the road to cancer: aneuploidy and the mitotic checkpoint | journal = Nature Reviews. Cancer | volume = 5 | issue = 10 | pages = 773–85 | date =2005-10 | pmid = 16195750 | doi = 10.1038/nrc1714 }}</ref>
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