Cell division

File:Divisome.jpg

Bacterial cell division happens through binary fission or through budding. The divisome is a protein complex in bacteria that is responsible for cell division, constriction of inner and outer membranes during division, and remodeling of the peptidoglycan cell wall at the division site. A tubulin-like protein, FtsZ plays a critical role in formation of a contractile ring for the cell division.Cell Division: The Cycle of the Ring, Lawrence Rothfield and Sheryl Justice, [https://www.cell.com/fulltext/S0092-8674(00)81899-1#:~:text=The%20bacterial%20cell%20cycle%20can,to%20cytokinesis%20and%20cell%20separation. CELL], [https://doi.org/10.1016/S0092-8674(00)81899-1 DOI]

{{See also|Alternation of generations}}

Cell division in eukaryotes is more complicated than in prokaryotes. If the chromosomal number is reduced, eukaryotic cell division is classified as meiosis (reductional division). If the chromosomal number is not reduced, eukaryotic cell division is classified as mitosis (equational division). A primitive form of cell division, called amitosis, also exists. The amitotic or mitotic cell divisions are more atypical and diverse among the various groups of organisms, such as protists (namely diatoms, dinoflagellates, etc.) and fungi.{{citation needed|date=May 2024}}

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In the mitotic metaphase (see below), typically the chromosomes (each containing 2 sister chromatids that developed during replication in the S phase of interphase) align themselves on the metaphase plate. Then, the sister chromatids split and are distributed between two daughter cells.{{citation needed|date=May 2024}}

In meiosis I, the homologous chromosomes are paired before being separated and distributed between two daughter cells. On the other hand, meiosis II is similar to mitosis. The chromatids are separated and distributed in the same way. In humans, other higher animals, and many other organisms, the process of meiosis is called gametic meiosis, during which meiosis produces four gametes. Whereas, in several other groups of organisms, especially in plants (observable during meiosis in lower plants, but during the vestigial stage in higher plants), meiosis gives rise to spores that germinate into the haploid vegetative phase (gametophyte). This kind of meiosis is called "sporic meiosis."{{citation needed|date=May 2024}}

File:Animal cell cycle-en.svg) and the cell cycle in animal cells.]]

Interphase is the process through which a cell must go before mitosis, meiosis, and cytokinesis.{{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}} Interphase consists of three main phases: G₁, S, and G₂. G₁ is a time of growth for the cell where specialized cellular functions occur in order to prepare the cell for DNA replication.{{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 }} There are checkpoints during interphase that allow the cell to either advance or halt further development. One of the checkpoint is between G₁ 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 G₂ 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.{{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 = }} In S phase, the chromosomes are replicated in order for the genetic content to be maintained.{{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}} During G₂, the cell undergoes the final stages of growth before it enters the M phase, where spindles are synthesized. The M phase can be either mitosis or meiosis depending on the type of cell. Germ cells, or gametes, undergo meiosis, while somatic cells 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 kinases. 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.{{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 }} There are three transition checkpoints the cell has to go through before entering the M phase. The most important being the G₁-S transition checkpoint. If the cell does not pass this checkpoint, it results in the cell exiting the cell cycle.{{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 }}

Prophase is the first stage of division. The nuclear envelope begins to be broken down in this stage, long strands of chromatin condense to form shorter more visible strands called chromosomes, the nucleolus disappears, and the mitotic spindle begins to assemble from the two centrosomes.{{cite journal | vauthors = Schermelleh L, Carlton PM, Haase S, Shao L, Winoto L, Kner P, Burke B, Cardoso MC, Agard DA, Gustafsson MG, Leonhardt H, Sedat JW | display-authors = 6 | title = Subdiffraction multicolor imaging of the nuclear periphery with 3D structured illumination microscopy | journal = Science | volume = 320 | issue = 5881 | pages = 1332–6 | date = June 2008 | pmid = 18535242 | pmc = 2916659 | doi = 10.1126/science.1156947 | bibcode = 2008Sci...320.1332S }} Microtubules associated with the alignment and separation of chromosomes are referred to as the spindle and spindle fibers. Chromosomes will also be visible under a microscope and will be connected at the centromere. During this condensation and alignment period in meiosis, the homologous chromosomes undergo a break in their double-stranded DNA at the same locations, followed by a recombination of the now fragmented parental DNA strands into non-parental combinations, known as crossing over.{{Cite journal|last1=Lewontin|first1=Richard C.|last2=Miller|first2=Jeffrey H.|last3=Gelbart|first3=William M.|last4=Griffiths|first4=Anthony J.F. | name-list-style = vanc |date=1999|title=The Mechanism of Crossing-Over|url=https://www.ncbi.nlm.nih.gov/books/NBK21271/ |journal=Modern Genetic Analysis }} This process is evidenced to be caused in a large part by the highly conserved Spo11 protein through a mechanism similar to that seen with topoisomerase in DNA replication and transcription.{{cite book|last=Keeney|first=Scott|name-list-style=vanc|title=Mechanism and control of meiotic recombination initiation|volume=52|date=2001|pages=[https://archive.org/details/currenttopicsind0000scha_v7u9/page/1 1–53]|publisher=Elsevier|isbn=9780121531522|doi=10.1016/s0070-2153(01)52008-6|pmid=11529427|series=Current Topics in Developmental Biology|url=https://archive.org/details/currenttopicsind0000scha_v7u9/page/1}}

Prometaphase is the second stage of cell division. This stage begins with the complete breakdown of the nuclear envelope which exposes various structures to the cytoplasm. This breakdown then allows the spindle apparatus growing from the centrosome to attach to the kinetochores on the sister chromatids. Stable attachment of the spindle apparatus to the kinetochores on the sister chromatids will ensure error-free chromosome segregation during anaphase.{{cite book |doi=10.1016/B978-0-12-821618-7.30064-5 |chapter=Mitosis in Animal Cells |title=Encyclopedia of Cell Biology |date=2016 |last1=Lian |first1=A.T.Y. |last2=Chircop |first2=M. |pages=298–313 |isbn=978-0-12-821624-8 }} Prometaphase follows prophase and precedes metaphase.

In metaphase, the centromeres of the chromosomes align themselves on the metaphase plate (or equatorial plate), an imaginary line that is at equal distances from the two centrosome poles and held together by complexes known as cohesins. Chromosomes line up in the middle of the cell by microtubule organizing centers (MTOCs) pushing and pulling on centromeres of both chromatids thereby causing the chromosome to move to the center. At this point the chromosomes are still condensing and are currently one step away from being the most coiled and condensed they will be, and the spindle fibers have already connected to the kinetochores.{{Cite web|url=https://www.sciencedaily.com/releases/2007/06/070611122252.htm|title=Researchers Shed Light On Shrinking Of Chromosomes|website=ScienceDaily | access-date=2019-04-14}} During this phase all the microtubules, with the exception of the kinetochores, are in a state of instability promoting their progression toward anaphase.{{Cite book |last1=Walter |first1=Peter |last2=Roberts |first2=Keith |last3=Raff |first3=Martin|last4=Lewis|first4=Julian|last5=Johnson|first5=Alexander|last6=Alberts|first6=Bruce | name-list-style = vanc |date=2002|chapter=Mitosis|url=https://www.ncbi.nlm.nih.gov/books/NBK26934/|title=Molecular Biology of the Cell|publisher=Garland Science | edition = 4th}} At this point, the chromosomes are ready to split into opposite poles of the cell toward the spindle to which they are connected.{{Cite book|title=Schaum's outlines : genetics|last=Elrod | first = Susan | name-list-style = vanc |date=2010 |publisher=Mcgraw-Hill |isbn=9780071625036 |edition=5th |location=New York |pages=8 |oclc=473440643}}

Anaphase is a very short stage of the cell cycle and it occurs after the chromosomes align at the mitotic plate. Kinetochores emit anaphase-inhibition signals until their attachment to the mitotic spindle. Once the final chromosome is properly aligned and attached the final signal dissipates and triggers the abrupt shift to anaphase. This abrupt shift is caused by the activation of the anaphase-promoting complex and its function of tagging degradation of proteins important toward the metaphase-anaphase transition. One of these proteins that is broken down is securin which through its breakdown releases the enzyme separase that cleaves the cohesin rings holding together the sister chromatids thereby leading to the chromosomes separating.{{cite book | vauthors = Brooker AS, Berkowitz KM | title = Cell Cycle Control | chapter = The Roles of Cohesins in Mitosis, Meiosis, and Human Health and Disease | series = Methods in Molecular Biology | volume = 1170 | pages = 229–66 | date = 2014 | pmid = 24906316 | pmc = 4495907 | doi = 10.1007/978-1-4939-0888-2_11 | publisher = Springer | location = New York | isbn = 9781493908875 }} After the chromosomes line up in the middle of the cell, the spindle fibers will pull them apart. The chromosomes are split apart while the sister chromatids move to opposite sides of the cell.{{Cite web|url=http://www.biology-pages.info/C/CellCycle.html|title=The Cell Cycle|website=www.biology-pages.info|access-date=2019-04-14}} As the sister chromatids are being pulled apart, the cell and plasma are elongated by non-kinetochore microtubules.{{cite book |title=Campbell Biology in Focus | location = Boston (Massachusetts) | publisher = Pearson | isbn = 978-0-321-81380-0 | date = 2014 | vauthors = Urry LA, Cain ML, Jackson RB, Wasserman SA, Minorsky PV, Reece JB }} Additionally, in this phase, the activation of the anaphase promoting complex through the association with Cdh-1 begins the degradation of mitotic cyclins.{{Cite journal |last=Barford |first=David |date=2011-12-12 |title=Structural insights into anaphase-promoting complex function and mechanism |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |language=en |volume=366 |issue=1584 |pages=3605–3624 |doi=10.1098/rstb.2011.0069 |pmid=22084387|pmc=3203452 }}

Telophase is the last stage of the cell cycle in which a cleavage furrow splits the cells cytoplasm (cytokinesis) and chromatin. This occurs through the synthesis of a new nuclear envelope that forms around the chromatin gathered at each pole. The nucleolus reforms as the chromatin reverts back to the loose state it possessed during interphase.{{cite journal | vauthors = Dekker J | title = Two ways to fold the genome during the cell cycle: insights obtained with chromosome conformation capture | journal = Epigenetics & Chromatin | volume = 7 | issue = 1 | pages = 25 | date = 2014-11-25 | pmid = 25435919 | pmc = 4247682 | doi = 10.1186/1756-8935-7-25 | doi-access = free }}{{cite journal | vauthors = Hetzer MW | title = The nuclear envelope | journal = Cold Spring Harbor Perspectives in Biology | volume = 2 | issue = 3 | pages = a000539 | date = March 2010 | pmid = 20300205 | pmc = 2829960 | doi = 10.1101/cshperspect.a000539 }} The division of the cellular contents is not always equal and can vary by cell type as seen with oocyte formation where one of the four daughter cells possess the majority of the duckling.{{Cite book|last=Gilbert|first=Scott F.| name-list-style = vanc |date=2000|chapter=Oogenesis|chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK10008/ |title=Developmental Biology |publisher=Sinauer Associates | edition = 6th }}

The last stage of the cell division process is cytokinesis. In this stage there is a cytoplasmic division that occurs at the end of either mitosis or meiosis. At this stage there is a resulting irreversible separation leading to two daughter cells. Cell division plays an important role in determining the fate of the cell. This is due to there being the possibility of an asymmetric division. This as a result leads to cytokinesis producing unequal daughter cells containing completely different amounts or concentrations of fate-determining molecules.{{cite journal | vauthors = Guertin DA, Trautmann S, McCollum D | title = Cytokinesis in eukaryotes | journal = Microbiology and Molecular Biology Reviews | volume = 66 | issue = 2 | pages = 155–78 | date = June 2002 | pmid = 12040122 | pmc = 120788 | doi = 10.1128/MMBR.66.2.155-178.2002 }}

In animals the cytokinesis ends with formation of a contractile ring and thereafter a cleavage. But in plants it happen differently. At first a cell plate is formed and then a cell wall develops between the two daughter cells.{{Cite journal |last=Smith |first=Laurie G |date=December 1999 |title=Divide and conquer: cytokinesis in plant cells |url=https://linkinghub.elsevier.com/retrieve/pii/S1369526699000229 |journal=Current Opinion in Plant Biology |language=en |volume=2 |issue=6 |pages=447–453 |doi=10.1016/S1369-5266(99)00022-9|pmid=10607656 |bibcode=1999COPB....2..447S |url-access=subscription }}

In Fission yeast (S. pombe) the cytokinesis happens in G1 phase.The Cell, G.M. Cooper; ed 2 [https://www.ncbi.nlm.nih.gov/books/NBK9876/ NCBI bookshelf], The eukaryotic cell cycle, [https://www.ncbi.nlm.nih.gov/books/NBK9876/ Figure 14.7]

File:Kinetochore.jpg in a human cell showing microtubules in green, chromosomes (DNA) in blue, and kinetochores in red. {{citation needed|date=May 2023}}]]

Cells are broadly classified into two main categories: simple non-nucleated prokaryotic cells and complex nucleated eukaryotic cells. Due to their structural differences, eukaryotic and prokaryotic cells do not divide in the same way. Also, the pattern of cell division that transforms eukaryotic stem cells into gametes (sperm cells in males or egg cells in females), termed meiosis, is different from that of the division of somatic cells in the body.

Image:Time-lapse video of dividing cells.gif.{{cite web |url=https://www.phiab.se/applications/cell-division |title = Phase Holographic Imaging of Cell Division |website=Internet archive |archive-url=https://web.archive.org/web/20130629210808/https://www.phiab.se/applications/cell-division |archive-date=29 June 2013 |url-status=dead}}]]

In 2022, scientists discovered a new type of cell division called asynthetic fission found in the squamous epithelial cells in the epidermis of juvenile zebrafish. When juvenile zebrafish are growing, skin cells must quickly cover the rapidly increasing surface area of the zebrafish. These skin cells divide without duplicating their DNA (the S phase of mitosis) causing up to 50% of the cells to have a reduced genome size. These cells are later replaced by cells with a standard amount of DNA. Scientists expect to find this type of division in other vertebrates.{{cite journal | vauthors = Chan KY, Yan CC, Roan HY, Hsu SC, Tseng TL, Hsiao CD, Hsu CP, Chen CH | display-authors = 6 | title = Skin cells undergo asynthetic fission to expand body surfaces in zebrafish| journal = Nature | volume = 605 | date = April 2022 | issue = 7908 | pages = 119–125 | pmid = 35477758 | doi = 10.1038/s41586-022-04641-0| bibcode = 2022Natur.605..119C | s2cid = 248416916 }}

DNA damage is detected and repaired at various points in the cell cycle. The G1/S checkpoint, G2/M checkpoint, and the checkpoint between metaphase and anaphase all monitor for DNA damage and halt cell division by inhibiting different cyclin-CDK complexes. The p53 tumor-suppressor protein plays a crucial role at the G1/S checkpoint and the G2/M checkpoint. Activated p53 proteins result in the expression of many proteins that are important in cell cycle arrest, repair, and apoptosis. At the G1/S checkpoint, p53 acts to ensure that the cell is ready for DNA replication, while at the G2/M checkpoint p53 acts to ensure that the cells have properly duplicated their content before entering mitosis.{{Cite book |last1=Senturk |first1=Emir |last2=Manfredi |first2=James J. |title=P53 Protocols |date=2013 |chapter=p53 and Cell Cycle Effects After DNA Damage |series=Methods in Molecular Biology (Clifton, N.J.) |volume=962 |pages=49–61 |doi=10.1007/978-1-62703-236-0_4 |issn=1064-3745 |pmc=4712920 |pmid=23150436|isbn=978-1-62703-235-3 }}

Specifically, when DNA damage is present, ATM and ATR kinases are activated, activating various checkpoint kinases.{{Cite journal |last1=Ding |first1=Lei |last2=Cao |first2=Jiaqi |last3=Lin |first3=Wen |last4=Chen |first4=Hongjian |last5=Xiong |first5=Xianhui |last6=Ao |first6=Hongshun |last7=Yu |first7=Min |last8=Lin |first8=Jie |last9=Cui |first9=Qinghua |date=2020-03-13 |title=The Roles of Cyclin-Dependent Kinases in Cell-Cycle Progression and Therapeutic Strategies in Human Breast Cancer |journal=International Journal of Molecular Sciences |volume=21 |issue=6 |pages=1960 |doi=10.3390/ijms21061960 |issn=1422-0067 |pmc=7139603 |pmid=32183020 |doi-access=free }} These checkpoint kinases phosphorylate p53, which stimulates the production of different enzymes associated with DNA repair.{{Cite journal |last1=Williams |first1=Ashley B. |last2=Schumacher |first2=Björn |date=2016 |title=p53 in the DNA-Damage-Repair Process |journal=Cold Spring Harbor Perspectives in Medicine |volume=6 |issue=5 |pages=a026070 |doi=10.1101/cshperspect.a026070 |issn=2157-1422 |pmc=4852800 |pmid=27048304}} Activated p53 also upregulates p21, which inhibits various cyclin-cdk complexes. These cyclin-cdk complexes phosphorylate the Retinoblastoma (Rb) protein, a tumor suppressor bound with the E2F family of transcription factors. The binding of this Rb protein ensures that cells do not enter the S phase prematurely; however, if it is not able to be phosphorylated by these cyclin-cdk complexes, the protein will remain, and the cell will be halted in the G1 phase of the cell cycle.{{Cite journal |last=Engeland |first=Kurt |date=2022 |title=Cell cycle regulation: p53-p21-RB signaling |journal=Cell Death & Differentiation |language=en |volume=29 |issue=5 |pages=946–960 |doi=10.1038/s41418-022-00988-z |pmid=35361964 |pmc=9090780 |issn=1476-5403|doi-access=free }}

If DNA is damaged, the cell can also alter the Akt pathway in which BAD is phosphorylated and dissociated from Bcl2, thus inhibiting apoptosis. If this pathway is altered by a loss of function mutation in Akt or Bcl2, then the cell with damaged DNA will be forced to undergo apoptosis.{{Cite journal |last1=Ruvolo |first1=P. P. |last2=Deng |first2=X. |last3=May |first3=W. S. |date=2001 |title=Phosphorylation of Bcl2 and regulation of apoptosis |url=https://www.nature.com/articles/2402090 |journal=Leukemia |language=en |volume=15 |issue=4 |pages=515–522 |doi=10.1038/sj.leu.2402090 |pmid=11368354 |s2cid=2079715 |issn=1476-5551|url-access=subscription }} If the DNA damage cannot be repaired, activated p53 can induce cell death by apoptosis. It can do so by activating the p53 upregulated modulator of apoptosis (PUMA). PUMA is a pro-apoptotic protein that rapidly induces apoptosis by inhibiting the anti-apoptotic Bcl-2 family members.{{Cite journal |last1=Jabbour |first1=A. M. |last2=Heraud |first2=J. E. |last3=Daunt |first3=C. P. |last4=Kaufmann |first4=T. |last5=Sandow |first5=J. |last6=O'Reilly |first6=L. A. |last7=Callus |first7=B. A. |last8=Lopez |first8=A. |last9=Strasser |first9=A. |last10=Vaux |first10=D. L. |last11=Ekert |first11=P. G. |date=2009 |title=Puma indirectly activates Bax to cause apoptosis in the absence of Bid or Bim |journal=Cell Death & Differentiation |language=en |volume=16 |issue=4 |pages=555–563 |doi=10.1038/cdd.2008.179 |pmid=19079139 |issn=1476-5403|doi-access=free }}

Multicellular organisms replace worn-out cells through cell division. In some animals, however, cell division eventually halts. In humans this occurs, on average, after 52 divisions, known as the Hayflick limit. The cell is then referred to as senescent. With each division the cells telomeres, protective sequences of DNA on the end of a chromosome that prevent degradation of the chromosomal DNA, shorten. This shortening has been correlated to negative effects such as age-related diseases and shortened lifespans in humans.{{cite journal | vauthors = Jiang H, Schiffer E, Song Z, Wang J, Zürbig P, Thedieck K, Moes S, Bantel H, Saal N, Jantos J, Brecht M, Jenö P, Hall MN, Hager K, Manns MP, Hecker H, Ganser A, Döhner K, Bartke A, Meissner C, Mischak H, Ju Z, Rudolph KL | display-authors = 6 | title = Proteins induced by telomere dysfunction and DNA damage represent biomarkers of human aging and disease | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 105 | issue = 32 | pages = 11299–304 | date = August 2008 | pmid = 18695223 | pmc = 2516278 | doi = 10.1073/pnas.0801457105 | bibcode = 2008PNAS..10511299J | doi-access = free }}{{cite journal | vauthors = Cawthon RM, Smith KR, O'Brien E, Sivatchenko A, Kerber RA | title = Association between telomere length in blood and mortality in people aged 60 years or older | journal = Lancet | volume = 361 | issue = 9355 | pages = 393–5 | date = February 2003 | pmid = 12573379 | doi = 10.1016/S0140-6736(03)12384-7 | s2cid = 38437955 }} Cancer cells, on the other hand, are not thought to degrade in this way, if at all. An enzyme complex called telomerase, present in large quantities in cancerous cells, rebuilds the telomeres through synthesis of telomeric DNA repeats, allowing division to continue indefinitely.{{cite journal | vauthors = Jafri MA, Ansari SA, Alqahtani MH, Shay JW | title = Roles of telomeres and telomerase in cancer, and advances in telomerase-targeted therapies | journal = Genome Medicine | volume = 8 | issue = 1 | pages = 69 | date = June 2016 | pmid = 27323951 | pmc = 4915101 | doi = 10.1186/s13073-016-0324-x | doi-access = free }}

File:1943 Device for micro-cinematography- under the direction of Kurt Michel, the first film on cell division is produced in a Zeiss laboratory with the aid of a phase-contrast microscope (6892933110).jpg

At the beginning of the 19th century, various hypotheses circulated about cell proliferation, which became observable in plant and animal organisms as a result of advances in microscopy. While the proliferation of cells on the inner side of old cells,Charles F. B. de Mirbel, 1813Pierre J. F. Turpin, 1825 the attachment of vesicles to existing cells,Matthias Jacob Schleiden, 1838 or crystallization in the intercellular spaceTheodor Schwann, 1839 were postulated as mechanisms of cell proliferation, cell division itself had to fight for its acceptance for decades.

The Belgian botanist Barthélemy Charles Joseph Dumortier must be regarded as the first discoverer of cell division. In 1832, he described cell division in simple aquatic plants (French 'conferve') as follows (translated from French to English):

"The development of the conferve is as simple as its structure; it takes place by the attachment of new cells to the old, and this attachment always takes place from the end. The terminal cell elongates more than the deeper cells; then the production of a lateral bisector takes place in the inner fluid, which tends to divide the cell into two parts, of which the deeper one remains stationary, while the terminal part elongates again, forms a new inner partition, and so on. Is the production of the middle partition originally double or single? It is impossible to determine this, but it is always true that it later appears double when united, and that when two cells naturally separate, each of them is closed at both ends."B. C. Dumortier: Recherches sur la structure comparée et le développement des animaux et des végétaux. Bruxelles 1832.

In 1835, the German botanist and physician Hugo von Mohl described plant cell division in much greater detail in his dissertation on freshwater and seawater algae for his PhD thesis in medicine and surgery:Hugo von Mohl: Ueber die Vermehrung der Pflanzen-Zellen durch Theilung. Tübingen 1835.

"Among the most obscure phenomena of plant life is the manner in which the newly developing cells are formed. [...] and so there is no lack of manifold descriptions and explanations of this process. [...] and that gaps that were found in the observations were filled in by overly bold conclusions and assumptions." (translated from German to English)

In 1838, the German physician and botanist Franz Julius Ferdinand Meyen confirmed the mechanism of cell division at the root tips of plants.Franz Julius Ferdinand Meyen: Neues System der Pflanzenphysiologie. Berlin 1838.

The German-Polish physician Robert Remak suspected that he had already discovered animal cell division in the blood of chicken embryos in 1841,Robert Remak: Bericht über die Leistungen im Gebiete der Physiologie. Hrsg.: Arch. Anat., Physiol. und wiss. Med. 1841. but it was not until 1852 that he was able to confirm animal cell division for the first time in bird embryos, frog larvae and mammals.Robert Remak: Ueber extracellulare Entstehung thierischer Zellen und über Vermehrung derselben durch Theilung. Hrsg.: Arch. Anat., Physiol. und wiss. Med. 1852.

In 1943, cell division was filmed for the first time{{cite book |last=Masters|first=Barry R| name-list-style = vanc |chapter=History of the Optical Microscope in Cell Biology and Medicine|date=2008-12-15|publisher=John Wiley & Sons, Ltd.|isbn=978-0470016176|doi=10.1002/9780470015902.a0003082|title=Encyclopedia of Life Sciences}} by Kurt Michel using a phase-contrast microscope.{{Citation|last=ZEISS Microscopy|title=Historic time lapse movie by Dr. Kurt Michel, Carl Zeiss Jena (ca. 1943)|date=2013-06-01|url=https://www.youtube.com/watch?v=Ge4k3uiB3qw| archive-url=https://ghostarchive.org/varchive/youtube/20211107/Ge4k3uiB3qw| archive-date=2021-11-07 | url-status=live|access-date=2019-04-15}}{{cbignore}}

• Cell fusion
• gametic fusion
• Cell growth
• Cyclin-dependent kinase
• Labile cells, cells that constantly divide
• Mitotic catastrophe

{{Reflist}}

• Morgan HI. (2007). "The Cell Cycle: Principles of Control" London: New Science Press.
• J.M.Turner Fetus into Man (1978, 1989). Harvard University Press. {{ISBN|0-674-30692-9}}
• [https://web.archive.org/web/20121230032903/http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html Cell division: binary fission and mitosis]
• McDougal, W. Scott, et al. Campbell-Walsh Urology Eleventh Edition Review. Elsevier, 2016.
• The [https://web.archive.org/web/20080604121440/http://cellimages.ascb.org/u/?%2Fp4041coll11%2C88 Mitosis and Cell Cycle Control Section] from the [https://web.archive.org/web/20091202210521/http://cellimages.ascb.org/cdm4/browse.php?CISOROOT=%2Fp4041coll11 Landmark Papers in Cell Biology] (Gall JG, McIntosh JR, eds.) contains commentaries on and links to seminal research papers on mitosis and cell division. Published online in the [http://cellimages.ascb.org/ Image & Video Library] of [http://www.ascb.org/ The American Society for Cell Biology]
• The [http://cellimages.ascb.org/ Image & Video Library] {{Webarchive|url=https://web.archive.org/web/20110610012208/http://cellimages.ascb.org/ |date=2011-06-10 }} of [http://www.ascb.org/ The American Society for Cell Biology] contains many videos showing the cell division.
• The [http://cellimagelibrary.org/browse/cellprocess/Cell%20Division Cell Division] of [http://cellimagelibrary.org the Cell Image Library]
• [http://www.alpine-plants-jp.com/himitunohanazono/ebine_himitu_3.htm Images : Calanthe discolor Lindl.] – Flavon's Secret Flower Garden
• [http://www.ebi.ac.uk/biomodels-main/BIOMD0000000005 Tyson's model of cell division] and a [http://www.ebi.ac.uk/biomodels-main/static-pages.do?page=ModelMonth%252FOctober2006%2FBIOMD0000000005_MM Description] on BioModels Database
• [http://wormweb.org/celllineage WormWeb.org: Interactive Visualization of the C. elegans Cell Lineage] – Visualize the entire set of cell divisions of the nematode C. elegans

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Category:Cell cycle

Category:Cellular processes

Category:Telomeres

Category:1835 in science

Category:1835 in the German Confederation