Chapter 46 Lecture Notes

  1. Gametogenesis in Male Review
    Like in female, controlled by __
    Need those two hormones, and testosterone to __
    • anterior pituitary hormones, FSH and LH
    • have gametogenesis
  2. I.Sperm cell is __(2n) reproduces by mitosis
    II.Enables male to do what?

    I.At some point, in the life on a  spermatogonia, it __--> __
    I.In commitment, what has to happen as part of commitment is __
    II. 2n (Chromosome number)/ 2n (DNA molecule)
    • spermatogonia
    • make many stem cells throughout life
    • comits to becoming a gameteà
    • primary spermatocyte
    • replication of genetic material
  3. Meiosis I: in male gametogenesis
    •   - primary spermatocyte (2n/4n)à
    •   - secondary spermatocyte (1n/ 2n)
  4. Meiosis II in male gametogenesis
    • Meiosis II:
    •   - four cells that are completely haploid (chromatids separate)à spermatids
    • Spermatogenesis is from top up to the last four haploid cells that do not resemble sperm:
  5. End of Meiosis II sperm
     - round, nondistinct cellsThey have to be streamlined into sperm= spermiogenesis, where they obtain their sperm shape
  6. One primary spermatocyteà makes what?

    He always has __
    • four sperm
    • spermatogonia, primary stem cells
  7. Gametogenesis in female

    • Mature all at same time
    • Meiosis and maturing at the same time
  8. Difference in results for male and female
    • end for female is larger and larger egg because she has to bring a dowry of structures that will be used by embryo in early development
    •   The sperm streamlines in gametogenesis in the male; gets smaller and only has cytoplasm
  9. Female gametogenesis begins in what?
    • Begins when she is in the womb (embryo)
    •   - in her ovary, all her stem cells commit to meiosis (oogoniaà primary oocytes) 
  10. When does each primary oocyte actually begin meiosis I?
    • when she is still in the womb
    •   - by the time she’s born, they are rested in prophase I, meiosis I= all of them
  11. What happens when she commits?
    • She begins Meiosisà stops at prophase I at birth
    •   Every primary oocyte is an immature (primary) follicle
  12. All commit to becoming __
    If the commitment is the same, it has to __
    • primary oocytes
    • replicate its genetic material
  13. Primary follicle is the ?
    primordial follicle
  14. What happens at puberty?
    , every month, one primary oocyte completes meiosis one
  15. What determines where in cell cytokinesis will happen?
    Where is the primary oocyte's nucleus? 
    Meiotic division in terms of location of nucleus?
    • site of nucleus
    • Primary oocyte’s nucleus is up top; meiotic division is horizontal 
  16. Contrast cytokinesis in male and female
    uneven cytokinesis in female, not male
  17. Result of meiosis I
    Secondary oocyte and first polar body (1n/2n)
  18. Function: of first polar body
    • (terminal cell): remove a set of homologs from the developing egg
    •   Get rid of a set of chromosomes
  19. Does the formation of just one ovum in female gametogenesis happen in all animals?
    How do we know its only one egg?
    • Doesn’t happen in all animals: some make four eggs
    • We have one child at a time
    • Other animals have litters
  20. True or False:

    Even though terminal cell, first polar body could go through meiosis IIà polar bodies
  21. Meiosis II for females
    • Secondary oocyte goes through meiosis II, producing one large cell; one small cell
    •   Small cell= second polar body
    •   Because of eccentric location of nucleusà result: large cell (ovum) and small cell (second polar body)
  22. Both ovum and second polar body are __n/__n
      Function of second polar body: 

    •  reduce the set of sister chromatids from the (secondary oocyte)à what remains is the completely haploid egg (ovum)
    •   Get rid of remaining set to make the ovum completely haploid
  23. End result in female of meiosis II
    • egg is one full set of haploid chromosomes
    • All polar bodies are 1n/1n
  24. Where does the secondary oocyte come from? 
    Primary oocyte
  25. What happens when the sperm enters the secondary oocyte?
    • it enables the secondary oocyte to complete meiosis II
    • The secondary oocyte is ovulated and enters the fallopian tube and meets the sperm there
  26. True or False: 
    The stem cell in a female exists after birth.
    false; does not
  27. How do the secondary oocyte and sperm relate?
    • Secondary oocyte= meiosis II if the sperm enters
    •  Needs sperm to complete meiosis II
    •   No spermà shed, not completed; it will never become an egg
  28. First polar body and meiosis II relation
    First polar body has no general function after it carries out it first; it generally doesn’t undergo meiosis II
  29. Size of ovum in relation to starting cell
    • Ovum is much larger than starting cell
    •   At end, when you have the mature ovum, it is much larger than the primary oocyte that began the process
    •   Part of the process of oogenesis is the accumulation of structures, so that it can foster early development
  30. Why must the egg have so many structures?
    • Embryonic genome does not turn out as quickly
    •   Has to rely on maternal messages, ribosomes, enzymes, etc. 
  31. Normal fertilization occurs in (be specific)= 
    ampulla of the fallopian tube
  32. The following cells have similar genetic constitutions:

    E. Both B and D
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Chapter 46 Lecture Notes
Chapter 46