Mitosis is a process where a single cell divides into two identical daughter cells cell division. The major purpose of mitosis is for growth and to replace worn out cells. If not corrected in time, mistakes made during mitosis can result in changes in the DNA that can potentially lead to genetic disorders.
Within each of the eukaryotic supergroupsmitosis of the open form can be found, as well as closed mitosis, except for Excavatawhich show exclusively closed mitosis.
Closed extranuclear pleuromitosis occurs in Trichomonadida and Dinoflagellata. Closed orthomitosis is found among diatomsciliatessome Microsporidiaunicellular yeasts and some multicellular fungi.
Semiopen pleuromitosis is typical of most Apicomplexa. Semiopen orthomitosis occurs with different variants in some amoebae Lobosa and some green flagellates e.
Open orthomitosis is typical in mammals and other Metazoaand in land plants ; but it also occurs in some protists. As a result, the former cell gets three copies of the chromosome, a condition known as trisomyand the latter will have only one copy, a condition known as monosomy.
On occasion, when cells experience nondisjunction, they fail to complete cytokinesis and retain both nuclei in one cell, resulting in binucleated cells.
The lagging chromatid is excluded from both nuclei and is lost. Therefore, one of the daughter cells will be monosomic for that chromosome. Endoreduplication or endoreplication occurs when chromosomes duplicate but the cell does not subsequently divide.
This results in polyploid cells or, if the chromosomes duplicates repeatedly, polytene chromosomes. Instead of being divided into two new daughter nuclei, the replicated chromosomes are retained within the original nucleus.
Platelet -producing megakaryocytes go through endomitosis during cell differentiation. Karyokinesis without cytokinesis originates multinucleated cells called coenocytes. Related cell processes[ edit ] Cell rounding[ edit ] Cell shape changes through mitosis for a typical animal cell cultured on a flat surface.
The cell undergoes mitotic cell rounding during spindle assembly and then divides via cytokinesis. Rounding also occurs in live tissue, as described in the text. Mitotic cell rounding In animal tissue, most cells round up to a near-spherical shape during mitosis. Generation of pressure is dependent on formin -mediated F-actin nucleation  and Rho kinase ROCK -mediated myosin II contraction,    both of which are governed upstream by signaling pathways RhoA and ECT2   through the activity of Cdk1.
Mitotic recombination[ edit ] Mitotic cells irradiated with X-rays in the G1 phase of the cell cycle repair recombinogenic DNA damages primarily by recombination between homologous chromosomes.
Evolution[ edit ] Some types of cell division in prokaryotes and eukaryotes There are prokaryotic homologs of all the key molecules of eukaryotic mitosis e.
Being a universal eukaryotic property, mitosis probably arose at the base of the eukaryotic tree. As mitosis is less complex than meiosismeiosis presumably arose after mitosis.
In relation to the forms of mitosis, closed intranuclear pleuromitosis seems to be the most primitive type, as it is the more similar to bacterial division. Polar microtubules, shown as green strands, have established a matrix around the currently intact nucleus, with the condensing chromosomes in blue.
The red nodules are the centromeres.
The nuclear membrane has just disassembled, allowing the microtubules to quickly interact with the kinetochores, which assemble on the centromeres of the condensing chromosomes. The centrosomes have moved to the poles of the cell and have established the mitotic spindle. The chromosomes have congressed at the metaphase plate.
Kinetochore microtubules pull the two sets of chromosomes apart, and lengthening polar microtubules push the halves of the dividing cell further apart, while chromosomes are condensed maximally. Reversal of prophase and prometaphase events and thus completing the cell cycle.Mitosis divides the nucleus so that both daughter cells are genetically identical.
In contrast, meiosis is a reduction division, producing genetically variable daughter cells that contain half the genetic information of the parent cell. Compare and Contrast Mitosis and Meiosis – Essay Sample Comparison of mitosis and meiosis is a common task for almost all biology classes.
Perhaps the reason for such an activity is to better understand these processed and to be able to tell them apart.
Essay about Mitosis and Meiosis Biology On multicellular eukaryotes there are two types of cell division, mitotic (consist of mitosis and cytokinesis) and meiosis, the major use of mitosis is for division at autonomous cell, meiosis is . Mitosis and meiosis essay.
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In the Mitosis lab an onion root was observed under a microscope to observe whether or not cell division takes place. Also, whether cells replicate in. Good Essays words | ( pages) | Preview The Link Between Cancer and Mitosis - The Link Between Cancer and Mitosis Cancer is one of the most common diseases in the developed countries, accounting for around one in four deaths.