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Encyclopedia > Cell division

Cell division is the process by which a cell, called the parent cell, divides into two cells, called daughter cells. Cell division is usually a small segment of a larger cell cycle. In meiosis however, a cell is permanently transformed and cannot divide again. Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... The cell cycle, or cell-division cycle (CDC), is the series of events in a eukaryotic cell between one cell division and the next. ... Not to be confused with miosis. ...


Cell division is the biological basis of life. For simple unicellular organisms such as the Amoeba, one cell division reproduces an entire organism. On a larger scale, cell division can create progeny from multicellular organisms, such as plants that grow from cuttings. Cell division also enables sexually reproducing organisms to develop from the one-celled zygote, which itself was produced by cell division from gametes. And after growth, cell division allows for continual renewal and repair of the organism. A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Amoeba, amÅ“ba, or ameba is a genus of protozoa that moves by means of temporary projections called pseudopods, and is well-known as a representative unicellular organism. ... Production of new individuals along a leaf margin of the air plant, Kalanchoë pinnata. ...   Sexual reproduction is a type of reproduction that results in increasing genetic diversity of the offspring. ... A zygote (Greek: ζυγωτόν) is a cell that is the result of fertilization. ... Gametes, from the ancient Greek γαμετης (spouse), are the specialized germ cells that come together during fertilization (conception) in organisms that reproduce sexually. ...


The primary concern of cell division is the maintenance of the original cell's genome. Before division can occur, the genomic information which is stored in chromosomes must be replicated, and the duplicated genome separated cleanly between cells. A great deal of cellular infrastructure is involved in keeping genomic information consistent between "generations". In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... This article is about the biological chromosome. ...

Contents

Variants

Three types of cell division

Cells are classified into two categories: simple, non-nucleated prokaryotic cells, and complex, nucleated eukaryotic cells. By virtue of their structural differences, eukaryotic and prokaryotic cells do not divide in the same way. Image File history File links Three_cell_growth_types. ... Image File history File links Three_cell_growth_types. ... Prokaryotes (pro-KAR-ee-oht) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ...


Furthermore, the pattern of cell division that transforms eukaryotic stem cells into gametes (sperm in males or ova in females) is different from that of eukaryotic somatic (non-germ) cells. Mouse embryonic stem cells with fluorescent marker. ... The signifier sperm can refer to: (mass noun, from Greek sperma = seed) a substance which consists of spermatozoa and which is a component of semen (mass noun) semen itself (informally, count noun with plural sperm or sperms) a single spermatozoon (= sperm cell) sperma ceti (Latin ceti, genitive of cetus = whale... A human ovum An ovum (loosely, egg or egg cell) is a female sex cell or gamete. ... The term somatic refers to the body, as distinct from some other entity, such as the mind. ...


Prokaryotic cells

Main article: binary fission

Prokaryotic cells are simpler in structure when compared to eukaryotic cells. They contain non-membranous organelles, lack a cell nucleus, and have a simplistic genome: only one circular chromosome of limited size. Therefore, prokaryotic cell division, a process known as binary fission, is fast. Binary fission Binary fission is the form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size, used by most prokaryotes. ... The eukaryotic cell nucleus. ... Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ... Binary fission Binary fission is the form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size, used by most prokaryotes. ...


The chromosome is duplicated prior to division. The two copies of the chromosome attach to opposing sides of the cellular membrane. Cytokinesis, the physical separation of the cell, occurs immediately. A cell that has almost completed cytokinesis. ...


Somatic eukaryotic cells

Main article: mitosis
  • Mitosis: The division of the nucleus, separating the duplicated genome into two sets identical to the parent's.
  • Cytokinesis: The division of the cytoplasm, separating the organelles and other cellular components.

Mitosis divides genetic information during cell division. ... Mitosis divides genetic information during cell division. ... A cell that has almost completed cytokinesis. ...

Degradation

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. Senescent cells deteriorate and die, causing the body to age. Cells stop dividing because the telomeres, protective bits of DNA on the end of a chromosome, become shorter with each division and eventually can no longer protect the chromosome. Cancer cells, on the other hand, are "immortal." An enzyme called telomerase, present in large quantites in cancerous cells, rebuilds the telomeres, allowing division to continue indefinitely. Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: wise man or knowing man) under the family Hominidae (the great apes). ... The Hayflick limit was discovered by Leonard Hayflick in 1965. ... It has been suggested that Longevity genes be merged into this article or section. ... A telomere is a region of highly repetitive DNA at the end of a chromosome that functions as a disposable buffer. ... Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Telomerase is an enzyme that adds specific DNA sequence repeats (TTAGGG in all vertebrates) to the 3 (three prime) end of DNA strands in the telomere regions, which are found at the ends of eukaryotic chromosomes. ...


Daughter chromosomes

During the metaphase stage of mitosis, chromosomes, which become aligned on the equatorial plane, take on the shape of an "X" as a result of a repelling force between chromosomes. The lobes of the chromosome in this shape are called 'sister chromatids'. The sister chromatids will be attached by a centromere. During metaphase, centromeres of the chromosomes will be aligned in the centre of the nucleus and spindle fibers will be attached to them. In the beginning of anaphase, spindle fibers contract so that the identical chromatids (sister chromatids), which where attached by centromere, will be separated. At this stage, each separated chromatid will act as a chromosome, and the two separated chromatids are called daughter chromosomes. An image of a newt lung cell stained with flourescent dyes during metaphase. ... Mitosis divides genetic information during cell division. ... Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ... A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. ... The centromere is a region of chromosomes with a special sequence and structure. ... The eukaryotic cell nucleus. ... In biology, spindle fibres are microtubules that are responsible for processes such as mitosis and meiosis. ... A lung cell of a newt during early anaphase of mitosis. ...


Phases

This article or section does not cite its references or sources. ... Prophase, with the mitotic spindles stained green and the cell nucleus and chromatin stained blue. ... An image of a newt lung cell stained with flourescent dyes during metaphase. ... A lung cell of a newt during early anaphase of mitosis. ... A cell during telophase that has almost completed cytokinesis. ... A cell that has almost completed cytokinesis. ...

See also

The cell cycle, or cell-division cycle (CDC), is the series of events in a eukaryotic cell between one cell division and the next. ... The term cell growth is used in two different ways in biology. ...

References

  1. Morgan DO. (2007) "The Cell Cycle: Principles of Control" London: New Science Press.
  2. J.M.Turner Fetus into Man (1978, 1989). Harvard University Press. ISBN 0-674-30692-9

External links

  • How Cells Divide: Mitosis vs. Meiosis
  • The Mitosis and Cell Cycle Control Section from the 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 Image & Video Library of The American Society for Cell Biology
  • The Video Collectionin the Image & Video Library of The American Society for Cell Biology contains many videos showing mitosis and cell division.

  Results from FactBites:
 
Cell division - encyclopedia article about Cell division. (2179 words)
Cell division is the process by which a cell (called the parent cell) divides into two cells (called daughter cells).
Cell division is usually a small segment of a larger cell cycle.
In some animals, however, cell division eventually halts (in humans this happens, on average, after 52 divisions, see Hayflick limit); the cell is then referred to as senescent.
  More results at FactBites »

 
 

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