Biologych8 - 8.1 Overview of Cell Division Mechanisms...

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1. Overview of Cell Division Mechanisms Challenge of dividing cell: daughter cell must get info encoded in parental DNA and enough cytoplasm to begin own operation - DNA “tells” which proteins to build; so m e are structural m at erials, so m e are enzy m es that s construction of organic co mpounds. - If cell does not inherit required info, will not grow/function properly - Parent cell’s cytoplas m already h as enzym es, organ elles, and other m et abolic m achinery. W d aught er cell inherits “blob” of cytoplas m, it is really g etting st art-up m achinery h at will kee running until it can use info in DNA for growing on its own Eukaryotic cells can’t split in two b/c single nucleus holds DNA - Split cytoplas m into daught er cells, but not until DNA is copied, sorted a nd p ackag ed Mitosis → nuclear division m ech anism that occurs in so m atic (body) cells - Basis of increas es in body size during growth, replace m ent of worn out or de ad cells, a nd tis repair - Many plants, anim als, fungi, a nd single-celled protists also reproduce as exually by mitosis Meiosis → nuclear division m ech anism that functions only in sexual reproduction - Preced es form ation of g a m et es (i.e. sp er m or e ggs) or spores; in co mplex anim als, ga m et es g er m cells Prokaryotic cells reproduce as exually by prokaryotic fission Every eukaryotic cell has charact eristic # DNA m olecules with att ached proteins, which tog form chromoso m es Chromoso m es duplicat ed before cell ent ers nuclear division Chromoso m e a nd copy att ached as sister chrom atids until late in nuclear division process Early in mitosis/m eiosis, chromoso m e coils back on itself repe at edly to a highly condensed by interactions b/w proteins a nd DNA Nucleoso m e → histone-DNA spool; unit of structural organization Centrom ere → pronounced constriction a pp e aring in a predictable location along its length; of att ach m e nt of sister chrom atids - On the surface of the centrom er e ar e found kinetochores → docking sites for microtubules t will m ove the chromoso m e during nuclear division -
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