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Meiosis

Meiosis. -Chapter 13. Cell Division. Chromosome number constant within a species. Humans - 46 chromosomes Apes - 48 chromosomes Cat - 38 chromosomes. Chromosomes are present in sets. Sex chromosomes and autosomes. Sex chromosomes :.

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Meiosis

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  1. Meiosis -Chapter 13

  2. Cell Division Chromosome number constant within a species Humans - 46 chromosomes Apes - 48 chromosomes Cat - 38 chromosomes Chromosomes are present in sets

  3. Sex chromosomes and autosomes Sex chromosomes: Represented differently in males and females Function in sex determination Autosomes: Chromosomes that are alike Not used in determining sex

  4. Male Karyotype Female Karyotype

  5. Number of chromosomes in a set is species specific (N) (N) Identifies the number of different chromosomes Haploid: (Gr. hapl, single) One set, or (N) chromosomes e.g., male honeybees, some rotifers, gametes Diploid: (Gr. di, two) Two sets, or (2N) chromosomes e.g., most animals; humans Polyploid: (Gr. polys, more) more than the diploid number e.g., few animals; brine shrimp

  6. Eukaryotic Cells Two types of cell division: A) Mitosis B) Meiosis

  7. A) Mitosis - body (somatic) cells - 2 daughter cells identical to parent - growth, and repair

  8. Result: two daughter cells identical to the original cell

  9. B) Meiosis - sex cells - two divisions - 4 haploid cells different from parent - gametes, genetic variability

  10. Genetic Recombination Variation Production of offspring with new combinations of traits Meiosis can diversify the genome (genetic material) 1) Crossing over 2) Independent assortment of chromosomes 3) Random fertilization

  11. 1) Crossing Over Result: 4 individual chromosomes Combination of DNA derived From 2 different parents

  12. 2) Independent Assortment

  13. 3) Random Fertilization

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