Editing Cell division (section)

=== Interphase ===
[[Interphase]] is the process through which a cell must go before mitosis, meiosis, and [[cytokinesis]].<ref>{{Cite book|title=Essentials of human anatomy and physiology| last = Marieb | first = Elaine Nicpon | name-list-style = vanc |date=2000 |publisher=Benjamin Cummings|isbn=978-0805349405|edition=6th|location=San Francisco|oclc=41266267}}</ref> Interphase consists of three main phases: [[G1 phase|G<sub>1</sub>]], [[S phase|S]], and [[G2 phase|G<sub>2</sub>]]. G<sub>1</sub> is a time of growth for the cell where specialized cellular functions occur in order to prepare the cell for DNA replication.<ref>{{cite journal | vauthors = Pardee AB | title = G1 events and regulation of cell proliferation | journal = Science | volume = 246 | issue = 4930 | pages = 603–8 | date = November 1989 | pmid = 2683075 | doi = 10.1126/science.2683075 | bibcode = 1989Sci...246..603P }}</ref> There are checkpoints during interphase that allow the cell to either advance or halt further development. One of the checkpoint is between G<sub>1</sub> and S, the purpose for this checkpoint is to check for appropriate cell size and any [[DNA damage]] . The second check point is in the G<sub>2</sub> phase, this checkpoint also checks for cell size but also the DNA replication. The last check point is located at the site of metaphase, where it checks that the chromosomes are correctly connected to the mitotic spindles.<ref>{{cite journal | vauthors = Molinari M | title = Cell cycle checkpoints and their inactivation in human cancer | journal = Cell Proliferation | volume = 33 | issue = 5 | pages = 261–74 | date = October 2000 | pmid = 11063129 | pmc = 6496592 | doi = 10.1046/j.1365-2184.2000.00191.x | url = }}</ref> In S phase, the chromosomes are replicated in order for the genetic content to be maintained.<ref>{{Cite book|title=The cell cycle : principles of control|last=Morgan | first = David Owen | name-list-style = vanc |date=2007|publisher=New Science Press|isbn=9780199206100|location=London|oclc=70173205}}</ref> During G<sub>2</sub>, the cell undergoes the final stages of growth before it enters the M phase, where [[Spindle apparatus|spindles]] are synthesized. The M phase can be either mitosis or meiosis depending on the type of cell. [[Germ cell]]s, or gametes, undergo meiosis, while [[somatic cell]]s will undergo mitosis. After the cell proceeds successfully through the M phase, it may then undergo cell division through cytokinesis. The control of each checkpoint is controlled by [[cyclin]] and [[cyclin-dependent kinase]]s. The progression of interphase is the result of the increased amount of cyclin. As the amount of cyclin increases, more and more cyclin dependent kinases attach to cyclin signaling the cell further into interphase. At the peak of the cyclin, attached to the cyclin dependent kinases this system pushes the cell out of interphase and into the M phase, where mitosis, meiosis, and cytokinesis occur.<ref>{{cite journal | vauthors = Lindqvist A, van Zon W, Karlsson Rosenthal C, Wolthuis RM | title = Cyclin B1-Cdk1 activation continues after centrosome separation to control mitotic progression | journal = PLOS Biology | volume = 5 | issue = 5 | pages = e123 | date = May 2007 | pmid = 17472438 | pmc = 1858714 | doi = 10.1371/journal.pbio.0050123 | doi-access = free }}</ref> There are three transition checkpoints the cell has to go through before entering the M phase. The most important being the G<sub>1</sub>-S transition checkpoint. If the cell does not pass this checkpoint, it results in the cell exiting the cell cycle.<ref>{{cite journal | vauthors = Paulovich AG, Toczyski DP, Hartwell LH | title = When checkpoints fail | journal = Cell | volume = 88 | issue = 3 | pages = 315–21 | date = February 1997 | pmid = 9039258 | doi = 10.1016/S0092-8674(00)81870-X | s2cid = 5530166 | doi-access = free }}</ref>