Cell Division; biology

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Cell Division; biology
2012-02-18 00:22:28

lecture notes
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  1. Interphase
    growing and getting ready to divide
  2. Mitosis
    cells dividing
  3. dividing cell does...(3)
    -precisely replicates its DNA

    -allocates the 2 copies f DNA to opposite ends of cell

    -seperates into 2 daughter cells that are same
  4. (interphase) G1
    -normal cell operation and growth

    -12 hrs
  5. (interphase) S
    DNA is replicated
  6. (interphase) G2
    • cell growth and preparation for cell division
    • -5.5 hours
  7. what happens during S phase...(3)
    -DNA double helix unwinds

    - protein wraps around DNA to make chromatin

    -chromatin condenses forming 2 chromatids.
  8. G2 features (3)
    -well defined nucleous bounded by nuclear envelope

    -one or more nucleoli

    -chromosomes that are loosely packed with chromatin fibers
  9. Cytokinesis
    -splitting of cytoplasm
  10. Prophase (4)
    -DNA begins to condense or thicken becoming more visible

    -nuclear membrane and nucleoli start to disappear

    -sister chromatids join togehter by centromeres

    -centrioles migrate to opposite ends of cell
  11. PArts of Chromosomes (4)



  12. Telomeres (3)
    chromosome tips

    -Consists of repeating sequence TTAGGG

    -protects chromosomes from breaking
  13. Centromere (3)
    -part where spindle fibers attach when cell divides

    -replicated toward the end of S stage

    -mostly structural role, maintain chromosome together
  14. Heterochromatin (2)
    dark areas of a chromosome

    -highly repetitive DNA sequences
  15. Euchromatin (3)
    light areas of chromosome

    -more protein-encoding sequences

  16. Sub-telomeres
    bridge gap between gene-rich regions and telomeres
  17. Kinetochore
    specialized region formed right before mitosis where spindle fibers can attach.
  18. Metaphase (3)
    spindle fibers extend from the poles toward the cells equator

    -microtubules become attached to the centromere on the chromosomes

    -early in this stage chromosomes develop kinetochores
  19. Karyotypes (3)
    method of displaying matching of homologous chromosomes

    -only visible if chromosomes are condense during replication

    -humans 22 pairs of autosomes, 1 pair of sex
  20. Anaphase (3)
    -spindle fibers begin to shorten seperating sister chromatids

    -seperated chromatids now called chromosomes

    -motor proteins move chromatids along microtubules
  21. Telophase
    -nuclear envelope appears to form

    -spindle fibers disappear

    -chromosomes decondense

    -2 daughter cells.
  22. Cytokinesis
    in animals, it occurs by a process called cleavage

    in plants, it occurs by the formation of cell plate