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Unformatted text preview: 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; some are structural materials, some are enzymes that speed construction of organic compounds.- If cell does not inherit required info, will not grow/function properly- Parent cells cytoplasm already has enzymes, organelles, and other metabolic machinery. When daughter cell inherits blob of cytoplasm, it is really getting start-up machinery hat will keep it running until it can use info in DNA for growing on its own Eukaryotic cells cant split in two b/c single nucleus holds DNA- Split cytoplasm into daughter cells, but not until DNA is copied, sorted and packaged Mitosis nuclear division mechanism that occurs in somatic (body) cells- Basis of increases in body size during growth, replacement of worn out or dead cells, and tissue repair- Many plants, animals, fungi, and single-celled protists also reproduce asexually by mitosis Meiosis nuclear division mechanism that functions only in sexual reproduction- Precedes formation of gametes (i.e. sperm or eggs) or spores; in complex animals, gametes form germ cells Prokaryotic cells reproduce asexually by prokaryotic fission Every eukaryotic cell has characteristic # DNA molecules with attached proteins, which together form chromosomes Chromosomes duplicated before cell enters nuclear division Chromosome and copy attached as sister chromatids until late in nuclear division process Early in mitosis/meiosis, chromosome coils back on itself repeatedly to a highly condensed form, by interactions b/w proteins and DNA Nucleosome histone-DNA spool; unit of structural organization Centromere pronounced constriction appearing in a predictable location along its length; site of attachment of sister chromatids- On the surface of the centromere are found kinetochores docking sites for microtubules that will move the chromosome during nuclear division- Defining characteristic; varies among chromosomes 2. I ntroducing the Cell Cycle...
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