Meiosis S1M1

  1. Meiosis only takes place in what type of cells
    Sex Cells
  2. Germ cells are also called
  3. The process of formation of gametes is called
  4. Primordial germ cells are
    The cells that give rise to the sex cells
  5. Where are primordial germ cells derived
    From the wall of the yolk sack
  6. Meiosis differs from mitosis in that
    • 1. They don't make identical copies the make different Cells
    • 2. They make only ½ Chromosome
    • 4. They are Haploid instead of Diploid
    • 3. Each germ cell only receives one copy of a chromosome
  7. What is chromosome condensation
    When the chromosomes are compacted to a more operable and identifiable form
  8. A chromatid
    One of the two identical copies of DNA making up a duplicated chromosome. When they separate, the strands are called sister chromatids.
  9. Name the stages of Prophase I of Meiosis
    • 1. Leptotene - condensation of chromatin, sister chromatids become connected by meiosis
    • 2. Zygotene - Synapsis of homologous chromatids and it continues in pachytene.
    • 3. Pachytene – Crossing-over of different chromatids
    • 4. Diplotene - Condensation still occurs and homologous chrom starts to separate from each other (disjunction). Chiasmata appears
    • 5. Diakinesis - Condensation of chrom. Nucleolus disappears and nuclear membrane disintegrates
    • Lazy Zebras Play Dominoes Dominica
  10. During Leptotene specific cohesion complexes called what pair the homologous Chromosomes
  11. Womens eggs are arrested in what phase until they are fertilized
    Diplotene stage one
  12. The incident for women to have downsyndrome children reaises quickly after what age
  13. How does Turners Syndrome happen
    When there is Monosomy = 23+22=45 chrom instead of the normal 46
  14. Where does nondisjunction occur for turners usually
    In the male sperm
  15. What is a significant cause of Spontaneous abortion
    Polyploidy – multiples of haploid # of chrom (69, 92, etc)
  16. What is the chromosomal and DNA amount for oocytes during the zygotene stage of meiosis I
    46 4n DNA
  17. What is the Significance of Meiosis
    • 1. Provides for constancy of chrom # for each generation
    • 2. Allows independent assortment of maternal and paternal chromosomes
    • 3. Allows for crossing over of genes – ‘ shuffling’ of genes
    • 4.Disturbances can occur during this process for e.g. Nondisjunction
  18. What is non-disjunstion
    When the chromosome pairs don't seperate or don't completely seperate which can lead to TRIsomy, MONOsomy, ect.
  19. 2n DNA represents
    46 represents
    • 2n = One pair of chromosomes
    • This is how we are

    46 = 2x23 (two of each chromosome)
Card Set
Meiosis S1M1
Cell Biology