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17 Cards in this Set
- Front
- Back
meiosis
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form of cell dicision that halves the number of chromosomes when forming specialized reproductive cells such as gametes or spores
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crossing over
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the exchange of reciprocal segments of DNA by homologous chromosomes of the beginning of meiosis; source of genetic recombination
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independent assortment
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random distribution of homologous chromosomes during meiosis
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spermatogenesis
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process by which gametes are produced in male animals
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sperm
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male gamete
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oogenesis
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process by which gametes are produced in female animals
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ovum
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mature egg cell
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Prophase One
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chromosomes condense; nuclear envelope breaks down; homologous chromosomes pair all along their length and then cross over
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Metaphase One
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Pairs of homologous chromosomes are moved by the spindle to the equator of the cell; homologous chromosomes, each made up of two chromatids remain together
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Anaphase One
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Homologous chromosomes seperate; as in mitosis the chromosomes of each pair are pulled to opposite poles of the cell by spindle fibers THE CHROMATIDS DO NOT SEPERATE OF THEIR CENTROMERES- EACH CHROMOSOME IS STILL COMPOSED OF TWO CHROMATIDS. THE GENETIC MATERIAL HAS RECOMBINED.
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Telephase One
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Individual chromosomes gather at each of the poles. In most organisms, the cytoplasm divides (cytokenesis) forming two new cells. Both cells or pores contain one chromosome from each pair of homologous chromosomes. The chromosomes do not replicate between miosis one and meiosis two
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Prophase Two
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A New Spindle forms around the chromosomes
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Metaphase Two
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Chromosomes line up along the equator and are attached at their centromeres to spinde fibers
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Anaphase Two
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Centromere divides and the chromatids (chromosomes) move to opposite poles of the cell
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Telophase Two
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Nuclear envelope forms around each set of chromosomes. The spindle breaks down, and the cell undergoes cytokenesis; the result of meiosis is four haploid cells
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Spermatogenesis LONG ONE
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Meiosis in males; occurs in testes; diploid cell first increases in size and becomes a large immature cell (germ cell); undergoes meiosis one and two
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Oogenesis LONG ONE
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Occurs in ovaries; one of the resulting cells after cytokenesis gives rise to an egg cell and the other becomes a polar body
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