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Cell division is the process of a biological cell (called a mother cell) dividing into two daughter cells. This leads to growth in multicellular organisms (the growth of tissue) and to procreation ( vegetative reproduction) in unicellular organisms. Prokaryotic cells divide by binary fission. Eukaryotic cells usually undergo a process of nuclear division, called mitosis, followed by division of the cell, called cytokinesis. A diploid cell may also undergo meiosis to produce haploid cells, usually four. Haploid cells serve as gametes in multicellular organisms, fusing to form new diploid cells.
Multicellular organisms replace worn-out cells through cell division. However, in some animals, cell division eventually halts, and the cell is then referred to as senescent. Senescent cells deteriorate and die, causing the body to age. Cells stop dividing because the telomeresA telomere is a region of highly repetitive DNA at the end of a chromosome, which functions as an aglet. Every time linear eukaryotic chromosomes are replicated, the DNA polymerase complex stops several hundred bases before the end; if it were not for tel, protective bits of DNA on the end of a chromosome2) Centromere. The point where the two chromatids touch, and where the microtubules attach. 3) Short arm. 4) Long arm. A chromosome is, minimally, a very long, continuous piece of DNA, which contains many genes, regulatory elements and other intervening n, become shorter with each division and eventually can no longer protect the chromosome. CancerFor other meanings of Cancer: see Cancer (disambiguation . apoptosis; cancer cells, however, avoid apoptosis. Cancer is a group of related diseases characterized by uncontrolled cell division. Currently, it is believed that cancers arise from both genetic cells, on the other hand, are "immortal." An enzymeAn enzyme is a protein, or protein complex, that catalyzes a chemical reaction. Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed to its steady state or completion much faster than it ot called telomeraseTelomerase is an enzyme that adds telomere repeats, ("TTAGGG" in all vertebrates) to the 5' ("five prime") end of DNA strands. The enzyme is a reverse transcriptase that carries it's own RNA template. By lengthening the strand before replication, cells wi allows them to continue dividing indefinitely.
1 See also
- Cell cycleThe cell cycle is the cycle of events in a eukaryotic cell from one cell division to the next. It consists of interphase, mitosis, and usually cell division. The cell cycle is regulated by cyclins and cyclin-dependent kinases. Hartwell, R. Timothy Hunt, a
- Cell growthThe term cell growth is used in two different ways in biology. When used in the context of reproduction of living cells the phrase "cell growth" is shorthand for the idea of "growth in cell numbers by means of cell reproduction. During cell reproduction o
2 External link
Cell biology
