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Bio Ch. 11 Meiosis

  1. Most eukaryotes reproduce sexually:
    Meiosis: a reduction division (# of chromosomes being halved)

    Fertilization: Syngamay (fusion of 2 gametes doubling chromosomes #)
  2. Who and when discovered meiosis:
    • 1880's - van bendend (w/ roundworms)
    • -Egg and sperm chromosomes were half of others
  3. Zygote:
    egg and sperm
  4. In life cycle of organism, meiosis and fertilization exist if:
    Cell has 2 copies of chromosomes (Diploid 2N)

    If cell has 1 copy of chromosomes (Haploid 1N)
  5. Fertilization=
    1N cell + 1N cell = 2N cell
  6. Meiosis:
    1 2N cell divides= 4 1N cells
  7. Diploid life cycle: (gameotogenesis)
    Image Upload 2
  8. Haploid Life Cycle:
    • Image Upload 4
    • many algae/fungi
  9. Spore:
    Gamete:
    can grow on its own

    Has to combine w/ another
  10. Alternation of generations:
    • Image Upload 6
    • -Plants/some algae
  11. Meiosis:
    • 1 2N cell --> 4 1N cell
    • Diploid --> Haploid
  12. Meiosis I: Prophase I
    • -Chromosomes condense
    • -Homologous chromosomes pair "synapsis"

    • TETRAD
    • Image Upload 8
    • Crossing over: Exchange of genetic material
  13. Metaphase I:
    Homologous pairs LINE UP on metaphase plate
  14. Anaphase I:
    Homologous chromosomes pulled apart
  15. Telophase I:
    • Get to final destination, Disapear and membrane forms
    • (down to half as many chromosomes as begining)
  16. Meiosis II: Prophase II
    Chromosomes re-appear
  17. Metaphase II:
    LINE UP
  18. Anaphase II:
    Sister chromosomes seperate from eachother
  19. Mitosis vs meiosis:
    Image Upload 10
  20. Sexual vs Asexual:
    • sexual: advantages - offspring are variable
    • disadvantages- expensive (calories) chancy

    • asexual: advantages - cheaper
    • disadvantages- offspring are uniform (bad for natural selection)
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Anonymous
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Bio Ch. 11 Meiosis
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CH. 11 Meiosis
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