Cell Division - Mitosis
|Embryology - 16 Feb 2019 Expand to Translate|
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- 1 Introduction
- 2 Some Recent Findings
- 3 Movies
- 4 Early Mitosis
- 5 Cell Changes
- 6 Mitosis Phases
- 7 Chromosome Changes
- 8 Cleavage of Zygote
- 9 Cytokinesis
- 10 Mitotic Spindle
- 11 Cell Organelles
- 12 References
- 13 Additional Images
- 14 Terms
- 15 External Links
- 16 Glossary Links
Normal cell division in all cells, except germ cells, occurs by 2 mechanical processes that initially divide the nucleus then the cell cytoplasm. This process produces two (daughter) cells that should be genetically identical to the parent cell.
- Mitosis segregation of chromosomes and formation of 2 nuclei
- Cytokinesis splitting of the cell as a whole into 2 daughter cells
- Recent Nobel Prizes- 2001 Cell Cycle, 2002 Cell Death
|Mitosis of the single zygote produces how many cells in the adult?|
| "In particular, the reported total cell number of a human being ranges between 1012 and 1016 and it is widely mentioned without a proper reference. ...A current estimation of human total cell number calculated for a variety of organs and cell types is presented. These partial data correspond to a total number of 3.72 × 1013."|
|Cell Division Links: meiosis | mitosis | Lecture - Cell Division and Fertilization | spermatozoa | oocyte | fertilization | zygote | Genetics|
Some Recent Findings
|More recent papers|
This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
This movie shows a cell dividing by mitosis with a fluorescently labelled protein that is located at the kinetochores and along the axes of the chromosome arms. This allows you to see the chromosomes and the linking region (kinetochore) between chromosome pairs and the mitotic spindle microtubules.
|In early development to the morula stage, cells are undergoing rapid cell mitotic divisions and do not have the usual G1 and G2 checkpoint regulation.
- Chromosome condensation
- Nuclear envelope breakdown
- Cytoskeleton reorganization
- Spindle formation (MT) Contractile ring (MF)
- Organelle redistribution
- Mitosis Energy
- Cell division uses up a lot of energy, so cells ensure they have enough resources to complete the job before committing to it.
- Based on light microscopy of living cells light and electron microscopy of fixed and stained cells
- 5 Phases - prophase, prometaphase, metaphase, anaphase, and telophase
- Cytokinesis 6th stage overlaps the end of mitosis
- not a mitotic phase (discussed in cell cycle)
- Chromosomes dispersed in nucleus
- Gene expression
- Cytoskeleton and cell organelles - Distributed and functioning
- Mitochondria undergo independent proliferation/division
- Chromosome DNA has been earlier duplicated (S Phase)
- Chromosomes begin condensing
- Chromosome pairs (chromatids) held together at centromere
- Microtubules disassemble
- Mitotic spindle begins to form
- 3 sets of microtubules - (+) ends point away from centrosome at each pole.
- astral microtubules - anchor the pole end in position
- kinetochore microtubules - connected to chromosomes
- polar microtubules - form the structure of the spindle apparatus
At end of prophase nuclear envelope breaks down
- Microtubules now enter nuclear region
- Nuclear envelope forms vesicles around mitotic spindle
- Kinetochores form on centromere attach to some MTs of spindle
At end of prometaphase chromosomes move to metaphase plate
- Kinetochore MTs align chromosomes in one midpoint plane.
- Astrin is a spindle-associated protein required for chromosome alignment at the metaphase plate.
Metaphase ends when sister kinetochores separate
- Separation of sister Kinetochores
- shortening of Kinetochore microtubules pulls chromosome to spindle pole.
- Katanin is a microtubule-severing complex involved with this stage of microtubule dynamics.
Anaphase ends as nuclear envelope (membrane) begins to reform.
- Chromosomes arrive at spindle poles
- Kinetochore MTs lost
- Condensed chromosomes begin expanding
- Continues through cytokinesis
Cleavage of Zygote
Mouse zygote mitosis
|First metaphase||First anaphase|
Cleavage of the zygote forms 2 blastomeres and is cleavage with no cytoplasm synthesis.
- special "embryonic" cell cycle S phases and M phases alternate without any intervening G1 or G2 phases (MSMSMSMS, adult MG1SG2) therefore individual cell volume decreases
Cell division within these cells is initially synchronous (at the same time), then becomes asynchronously (at different times).
- slow- centre cells, larger fast- peripheral cells
- Links: Zygote | Cell Division - Mitosis | Movie - Early Cell Division | Movie - Week 1 Cell Cleavage | Carnegie stage 1
- Division of cytoplasmic contents
- Contractile ring forms at midpoint under membrane
- Microfilament ring - contracts forming cleavage furrow
- myosin II is the motor
- Eventually fully divides cytoplasm
Spindle assembly motors
Microtubule (MT)-bound motors promote bipolar spindle formation, whereas chromosome-associated motors drive proper kinetochore orientation and chromosome movement to the equator.
|Box 1||Box 2||Box 3||Box 4||Box 5|
|Motor-dependent mechanisms establish bipolarity as Eg5 (kinesin-5) motors slide antiparallel microtubules apart with their minus ends leading and their plus ends directed toward the spindle equator.||Minus end–directed motors such as dynein move microtubules poleward with their minus ends leading, thereby incorporating K-fibers into the spindle and focusing spindle poles.||Kinetochore-associated dynein transports chromosomes along astral microtubules toward the spindle poles from the periphery.||Plus end–directed chromokinesins (kinesin-4 and -10) eject chromosome arms outward.||CENP-E (kinesin-7) transports unattached kinetochores toward the equator along spindle microtubules. MTOC, microtubule organizing centre.|
- Divide independently of cell mitosis
- distributed into daughter cells
- localise at spindle poles
Peroxisome (red) location at Interphase (a) and during Mitosis (b and c)
- Associated with nuclear membrane.
- 2 processes - disassembly and reassembly
- Golgi stack undergoes a continuous fragmentation process
- fragments are distributed into daughter cells
- are reassembled into new Golgi stacks
- Unstacking - mediated by two mitotic kinases (cdc2 and plk)
- Vesiculation - mediated by COPI budding machinery ARF1 and the coatomer complex
- Fusion - formation of single cisternae by membrane fusion
- Restacking - requires dephosphorylation of Golgi stacking proteins by protein phosphatase PP2A
- McCoy RC. (2017). Mosaicism in Preimplantation Human Embryos: When Chromosomal Abnormalities Are the Norm. Trends Genet. , 33, 448-463. PMID: 28457629 DOI.
- Tachikawa M & Mochizuki A. (2017). Golgi apparatus self-organizes into the characteristic shape via postmitotic reassembly dynamics. Proc. Natl. Acad. Sci. U.S.A. , 114, 5177-5182. PMID: 28461510 DOI.
- Clever M, Funakoshi T, Mimura Y, Takagi M & Imamoto N. (2012). The nucleoporin ELYS/Mel28 regulates nuclear envelope subdomain formation in HeLa cells. Nucleus , 3, 187-99. PMID: 22555603 DOI.
- Tavormina PA, Côme MG, Hudson JR, Mo YY, Beck WT & Gorbsky GJ. (2002). Rapid exchange of mammalian topoisomerase II alpha at kinetochores and chromosome arms in mitosis. J. Cell Biol. , 158, 23-9. PMID: 12105179 DOI.
- Kiessling AA, Bletsa R, Desmarais B, Mara C, Kallianidis K & Loutradis D. (2009). Evidence that human blastomere cleavage is under unique cell cycle control. J. Assist. Reprod. Genet. , 26, 187-95. PMID: 19288185 DOI.
- Jacobs K, Van de Velde H, De Paepe C, Sermon K & Spits C. (2017). Mitotic spindle disruption in human preimplantation embryos activates the spindle assembly checkpoint but not apoptosis until Day 5 of development. Mol. Hum. Reprod. , 23, 321-329. PMID: 28159965 DOI.
- Wei Y, Multi S, Yang CR, Ma J, Zhang QH, Wang ZB, Li M, Wei L, Ge ZJ, Zhang CH, Ouyang YC, Hou Y, Schatten H & Sun QY. (2011). Spindle assembly checkpoint regulates mitotic cell cycle progression during preimplantation embryo development. PLoS ONE , 6, e21557. PMID: 21720555 DOI.
- Russan NM. Let's Build a Spindle. ASCB Image & Video Library. 2008;CYT-190. Available at: http://cellimages.ascb.org/u?/p4041coll12,521
- <pubmed>21321204</pubmed>| PMC2132672 | PNAS
- Heald R & Khodjakov A. (2015). Thirty years of search and capture: The complex simplicity of mitotic spindle assembly. J. Cell Biol. , 211, 1103-11. PMID: 26668328 DOI.
- Kredel S, Oswald F, Nienhaus K, Deuschle K, Röcker C, Wolff M, Heilker R, Nienhaus GU & Wiedenmann J. (2009). mRuby, a bright monomeric red fluorescent protein for labeling of subcellular structures. PLoS ONE , 4, e4391. PMID: 19194514 DOI.
- Tang D, Mar K, Warren G & Wang Y. (2008). Molecular mechanism of mitotic Golgi disassembly and reassembly revealed by a defined reconstitution assay. J. Biol. Chem. , 283, 6085-94. PMID: 18156178 DOI.
Search Pubmed: mitosis
|Cell Division Terms|
|Meiosis | Mitosis
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- Nature - Cell Division Milestones
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Cite this page: Hill, M.A. (2019, February 16) Embryology Cell Division - Mitosis. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Cell_Division_-_Mitosis
- © Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G