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1
|
|
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2
|
- Cell division by which eggs and sperm are produced.
- The production of sex cells, which are not genetically identical,
through a series of cell divisions.
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3
|
- Ensures that humans have the same number of chromosomes in each
generation.
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4
|
- It is a two-step process that reduces the chromosome number by half—from
46 to 23—to form sperm and egg cells.
- This is a reduction in genetic material.
|
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5
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- When the sperm and egg cells join at fertilization, each contributes 23
chromosomes so the resulting embryo will have the usual 46.
|
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6
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- Meiosis also allows genetic variation through a process of DNA shuffling
while the cells are dividing.
|
|
7
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- TWO divisions
- ONE DNA replication
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8
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- Interphase: Before meiosis begins, genetic material is duplicated.
- First division of meiosis
- Prophase 1: Duplicated chromatin condenses. Each chromosome consists of
two, closely associated sister chromatids. Crossing over can occur
during the latter part of this stage.
- Metaphase 1: Homologous chromosomes align at the equatorial plate.
- Anaphase 1: Homologous pairs separate with sister chromatids remaining
together.
- Telophase 1: Two daughter cells are formed with each daughter
containing only one chromosome of the homologous pair.
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9
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- Second division of meiosis: Gamete formation
- Prophase 2: DNA does not replicate.
- Metaphase 2: Chromosomes align at the equatorial plate.
- Anaphase 2: Centromeres divide and sister chromatids migrate separately
to each pole.
- Telophase 2: Cell division is complete. Four haploid daughter cells are
obtained.
- One parent cell produces four daughter cells. Daughter cells have half
the number of chromosomes found in the original parent cell and with
crossing over, are genetically different.
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10
|
|
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11
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- Where a section of one chromosome switches places with the same section
from the other chromosome of the pair.
- Recombination
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12
|
|
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13
|
|
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14
|
- http://www.johnkyrk.com/meiosis.html
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|
15
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- http://www.csuchico.edu/~jbell/Biol207/animations/meiosis.html
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16
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Notes
