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Part 1: Genes, Chromosomes, and Heredity Mitosis and Meiosis Review
  1. In prokaryotes such as Escherichia coli, the genetic material is organized as a long circular molecule located in a area.
  2. In eukaryotes, DNA is transmitted from one generation of cells to the next by mitosis, which produces diploid cells, and meiosis, which produces haploid or spores.
  3. Fusion of two gametes at fertilization results in a diploid .
  4. In somatic cells, chromosomes exist in pairs. Such cells are (2n) and contain two copies, or , of each gene.
  5. Somatic cells undergo a cell : an actively dividing stage called alternates with an .
  6. In the cell may become nondividing or engage in duplication of , organelles, and other cell components in preparation for the next division.
  7. Mitosis consists of division (karyokinesis), which can be broken into five discrete stages, followed by division (cytokinesis).
    • In , the centrioles divide and move apart, the nuclear envelope breaks down, and the chromatin condense and become visible .
    • In , the chromosomes move to the equatorial plane of the cell.
    • In , the chromosomes are aligned at the equatorial plane.
    • In , sister chromatids separate from each other and migrate to opposite poles.
    • In , the separated daughter complete migration to opposite poles of the cell, and divides the cell in two.
  8. Mitosis produces two diploid daughter cells that are genetically identical. Mitosis review.
  9. Meiosis produces haploid and requires two rounds of cell division.
    • Meiosis I is the chromosome division and produces two cells with two still attached to the chromosomes.
    • Meiosis II is an division and each cell from Meiosis I produces two more cells each with one .
    Meiosis review and comparison with mitosis.
  10. Sexual reproduction produces genetic by several mechanisms.
    • In independent , each pair of chromosomes sorts its into daughter cells independently, giving 223 (about million) combinations in humans.
    • The random fusion of gametes during produces a zygote with 223 x 223, or over trillion, combinations of chromosomes.
    • Crossing over produces chromosomes that carry genes derived from different parents, increasing genetic variation even more.
  11. In animals, sexual reproduction involves the of haploid to produce diploid reproductive individuals.
    • Male gametes are produced by in the .
    • Female gametes are produced by in the .
  12. In plants, sexual reproduction alternates between a multicellular diploid generation with a multicellular haploid generation.
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