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Bio Ch. 11 Meiosis
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Most eukaryotes reproduce sexually:
Meiosis: a reduction division (# of chromosomes being halved)
Fertilization: Syngamay (fusion of 2 gametes doubling chromosomes #)
Who and when discovered meiosis:
1880's - van bendend (w/ roundworms)
-Egg and sperm chromosomes were half of others
Zygote:
egg and sperm
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)
Fertilization=
1N cell + 1N cell = 2N cell
Meiosis:
1 2N cell divides= 4 1N cells
Diploid life cycle: (gameotogenesis)
Haploid Life Cycle:
many algae/fungi
Spore:
Gamete:
can grow on its own
Has to combine w/ another
Alternation of generations:
-Plants/some algae
Meiosis:
1 2N cell --> 4 1N cell
Diploid --> Haploid
Meiosis I: Prophase I
-Chromosomes condense
-Homologous chromosomes pair "synapsis"
TETRAD
Crossing over
: Exchange of genetic material
Metaphase I:
Homologous pairs LINE UP on metaphase plate
Anaphase I:
Homologous chromosomes pulled apart
Telophase I:
Get to final destination, Disapear and membrane forms
(down to half as many chromosomes as begining)
Meiosis II: Prophase II
Chromosomes re-appear
Metaphase II:
LINE UP
Anaphase II:
Sister chromosomes seperate from eachother
Mitosis vs meiosis:
Sexual vs Asexual:
sexual
: advantages - offspring are variable
disadvantages- expensive (calories) chancy
asexual
: advantages - cheaper
disadvantages- offspring are uniform (bad for natural selection)
Author
Anonymous
ID
138904
Card Set
Bio Ch. 11 Meiosis
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CH. 11 Meiosis
Updated
2012-03-01T17:13:12Z
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