The Process of Meiosis for Sperm Cells
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| As meiosis begins (A), DNA replicates as in mitotic cell division.
However, before the replicated arms split apart, one member of each pair
of homologous chromosomes moves to become part of each first-generation
daughter cell (B). Once the first generation of daughter cells is established,
DNA replicas split as part of the second meiotic division (C). Thus, one
replica of one member of the pair of homologous chromosomes is contributed
to each second- generation daughter cell (D). From these two successive
divisions, four cells, each with twenty-three chromosomes, are produced.
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Cell with forty-six chromosomes (only one pair of homologous chromosomes is shown here).
Each member of the pair has begun to replicate similar to mitotic cell division.
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First meiotic cell division begins but does not proceed as in mitosis.
Instead of the replicated chromosome splitting apart, one member of each
homologous pair becomes a part of the first-generation daughter cell.
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The second meiotic division proceeds after the first is completed;
now the replicated chromosome acquired in the first-generation
daughter cell splits apart.
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Each of the four gametes produced by the two-step
process now has acquired one member of the pair of
homologous chromosomes.
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| A |
B |
C |
D |
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Materials from, Bukatko, Child Development, 4th ed., displayed with special permission of Houghton Mifflin Company. All Rights Reserved.
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