Meiosis- gamete formation

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Meiosis- gamete formation

• Mader Chapter 17.3

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Mitosis does not alter the chromosomal makeup of
cells
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Chromosome number must be reduced when gametes
are produced
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Meiosis separates homologous chromosomes
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There are 2N Possible arrangements of homologues
Four of the eight possible arrangements for a N
3 organism are shown above. Each Arrangement?2
gametes so there are 8 possible gametes!
Humans have 23 pairs of homologous chromosomes
N23 There are 223 possible arrangements of
homologues 8,388,608
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Crossing over generates even more diversity
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Meiosis

• Separates homologous chromosomes
• Chromosome number goes from 2N ?N
• Generates a very diverse set of gametes each of
  which contains a nearly unique set of maternal
  and paternal genes

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Spermatogenesis
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Human ova are ovulated arrested in meiotic
prophase II
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The human life cycle