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Why do chromosomes coil during mitosis?
to allow the chromosomes to move without becoming entangled and breaking
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Mitosis is the way in which _______ cells divide
somatic (non-sex)
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Meiosis is:
a special type of cell division used in sexual reproduction for the formation of gametes
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Karyotype:
image of a person's chromosomes
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Human cells have ___, making up ___ pairs of homologous chromosomes
46, 23
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Which human chromosome was the first to be sequenced in its entirety?
22
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What are the phases of meiosis I?
Prophase I, Metaphase I, Anaphase I, Telophase I, and Cytokinesis
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Prophase I (meiosis)
- the chromosomes begin to condense and pair up
- the chromosomes begin crossing over
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Metaphase I (meiosis)
homologue pairs—not individual chromosomes—line up at the metaphase plate for separation
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Anaphase I (meiosis)
- the homologues are pulled apart and move apart to opposite ends of the cell
- The sister chromatids of each chromosome remain attached to one another and don't come apart
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Telophase I and cytokinesis (meiosis)
- the chromosomes arrive at opposite poles of the cell
- two haploid cells form
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Chiasmata
the X-shaped structure formed at the point below the brain where the two optic nerves cross over each other
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What are the phases of meiosis II?
prophase II, metaphase II, anaphase II, telophase II, and cytokinesis (same as meiosis I)
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Meiosis II:
- separates sister chromatids
- results in four haploid daughter cells containing unduplicated chromosomes
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Diploid cell:
a cell that contains two sets of chromosomes
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Haploid cell:
a cell that contains a single set of chromosomes
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Meiosis-How is variability generated?
- Independent assortment of chromosomes
- Crossing over
- Random fertilization
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The fruit fly has four pairs of chromosomes. The house fly has six. In which species would you expect to see more genetic variation among the progeny?
the house fly
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