Bio 93 Lecture 19

  1. Why do chromosomes coil during mitosis?
    to allow the chromosomes to move without becoming entangled and breaking
  2. Mitosis is the way in which _______ cells divide
    somatic (non-sex)
  3. Meiosis is:
    a special type of cell division used in sexual reproduction for the formation of gametes
  4. Karyotype:
    image of a person's chromosomes
  5. Human cells have ___, making up ___ pairs of homologous chromosomes
    46, 23
  6. Which human chromosome was the first to be sequenced in its entirety?
  7. What are the phases of meiosis I?
    Prophase I, Metaphase I, Anaphase I, Telophase I, and Cytokinesis
  8. Prophase I (meiosis)
    • the chromosomes begin to condense and pair up
    • the chromosomes begin crossing over
  9. Metaphase I (meiosis)
    homologue pairs—not individual chromosomes—line up at the metaphase plate for separation
  10. 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
  11. Telophase I and cytokinesis (meiosis)
    • the chromosomes arrive at opposite poles of the cell
    • two haploid cells form
  12. Chiasmata
    the X-shaped structure formed at the point below the brain where the two optic nerves cross over each other
  13. What are the phases of meiosis II?
    prophase II, metaphase II, anaphase II, telophase II, and cytokinesis (same as meiosis I)
  14. Meiosis II:
    • separates sister chromatids
    • results in four haploid daughter cells containing unduplicated chromosomes
  15. Diploid cell:
    a cell that contains two sets of chromosomes
  16. Haploid cell:
    a cell that contains a single set of chromosomes
  17. Meiosis-How is variability generated?
    • Independent assortment of chromosomes
    • Crossing over
    • Random fertilization
  18. 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
Card Set
Bio 93 Lecture 19
Midterm 2