POGIL Cell Biology Activity 7 – Meiosis/Gametogenesis
MODEL 1:
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karyotype
Meiosis
Mitosis
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POGIL Cell Biology Activity 7 – Meiosis/Gametogenesis
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MODEL 2, Part 1: Mammalian Spermatogenesis
The trapezoid below represents a small portion of the wall of a "seminiferous tubule" within
the testis. The cells in each of the panels are all originally derived from the single cell in panel
1. (There would be many more cells present, but they are not shown for simplicity.)
1
2
3
4
5
6
7
8
9
Outside of tubule
Lumen of tubule
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POGIL Cell Biology Activity 7 – Meiosis/Gametogenesis
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MODEL 2 Part 2: Male Mammalian Reproductive Tract
vas
deferens
epididymis
The lumen of the seminiferous tubules
all join and drain into the tubules of
the epididymis, then into the vas
deferens, which later joins the urethra.
testis (plural: testes)
seminiferous
tubules
(cut)
Courtesy of: Dr. E. Kent
Christensen, U. of Michigan
lumen of
seminiferous
tubule
sperm
This portion shown
expanded in part 1
of Model 2
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POGIL Cell Biology Activity 7 – Meiosis/Gametogenesis
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MODEL 3: Mammalian Oogenesis
This is a time lapse of an ovary showing one "follicle" as it develops from immaturity to
ovulation. The follicle starts in panel 1 as a small sphere of "follicle cells" surrounding the
oocyte. In each panel, chromosomes within the oocyte are shown as an inset. (There are
actually thousands of follicles in each mammalian ovary).
1
2
3
4
5
6
7
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POGIL Cell Biology Activity 7 – Meiosis/Gametogenesis
Model 1 questions:
1. Using the same type of cartoon as model 1,
draw an "unreplicated", condensed chromosome.
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2. Draw a replicated, condensed chromosome:
3. Circle a homologous pair in the karyotype. Remember that one of these chromosomes came
from the male parent and the other from the female parent. These two chromosomes carry the
same genes! (But can have different alleles on each homolog.)
4. For this organism, its chromosome number is 2N= _____.
5. Label every cell in Model 1 as either diploid (2N, two homologs of each chromosome) or
haploid (1N, one homolog of each chromosome).
6. Label each cell in Model 1 as having either replicated (R) or unreplicated (U) chromosomes.
7. What do homologs do during meiosis that does not occur during mitosis?
8. List two differences between the final products of mitosis and meiosis:
_________________________
_________________________
Model 2, part 1 questions:
Examine both parts of model 2 to orient yourself to the diagram in part 1.
9. Does meiosis or mitosis occur between panels 1 and 2? _____________________
10. Follow the darkly outlined cell from panels 2 through 7.
a. Are these cells going through meiosis or mitosis?____________
b. Describe these cells' movement in the wall of the tubule over time:
11. Draw in the chromosomes in their proper states in all of the unfilled cells in panels 7-9
(except for the differentiated sperm - shaded).
12. Label cells in various panels of Model 2 with the best choice from the definitions below.
- 1° Spermatocyte – sperm precursor, it is going through Meiosis I
- 2° Spermatocyte – sperm precursor, it is going through Meiosis II
- Spermatogonium – stem cell, it divides to produce new spermatocytes
- Spermatid – sperm precursor, it has completed Meiosis
- Sperm – fully differentiated cell
13. Suggest a reason why both of the daughter cells of the division in panel 1-2 do NOT
continue on through the same process. (Hint – think of the reproductive lifespan of males.)
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POGIL Cell Biology Activity 7 – Meiosis/Gametogenesis
Model 2, part 2 questions:
14. In which part of the male reproductive system are sperm made? (Circle ONE)
vas deferens
epididymis
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testis
15. Why do sperm have to differentiate at the inner edge of the wall of the seminiferous tubule
(as opposed to the outer edge?)
16. Briefly diagram the path of sperm travel from differentiation to exiting the body.
Your TA will discuss the function of the epididymis in the gametogenesis lab.
Model 3 questions:
16. In panel 1, there are two types of cells shown in the follicle, one large one surrounded by
many smaller ones. Shade the large one. This is the developing oocyte. The smaller ones are
called "follicle cells".
17. How does the number of oocytes in the follicle change over the 7 panels? _______________
How does the number of follicle cells in the follicle change over the 7 panels? ____________
18. What type of cell division is the oocyte going through? ___________________
Assuming follicle cells all have the same identical set of
chromosomes, what type of cell division are the follicle cells going through? _____________
19. Follicle cells surrounding the oocyte transfer protein, mRNA and nutrients into the
oocyte, which in turn grows larger. Suggest a reason for this intensive "stockpiling" of
resources in the oocyte.
20. Starting at panel 4, a fluid is being released into increase the size of the
follicle. Is the oocyte or are the follicle cells more likely to release this fluid? ____________
21. a. Panel 7 shows ovulation. Has the released oocyte completed meiosis? __________
b. Meiosis I produced 2 daughter cells, but only one cell received cytoplasm and
organelles. The other daughter is a "polar body". Will the polar body survive? _______
c. Compare to spermatogenesis: Is the released oocyte a 1° or 2° oocyte? __________
d. Suggest a reason for the huge increase in fluid volume in the follicle prior to ovulation.
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POGIL Cell Biology Activity 7 – Meiosis/Gametogenesis
On Your Own:
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1. Go back to model 2, part 1. List three things that change when spermatids develop into
differentiated sperm.
__________________________
__________________________
__________________________
2. Compare spermatogenesis with oogenesis. List three things that are different between the
two processes.
__________________________
__________________________
__________________________
3. In the cell to the right, a cell from a diploid animal
is in the process of dividing.
a. This cell is completing… (Circle one)
mitosis
meiosis I
meiosis II
b. The 2 daughter cells produced by this cell division are: (Circle one)
haploid
diploid
c. This cell comes from a species of ant in which males are haploid, females are diploid.
i. This cell is taken from a... (Circle ONE)
female
male
ii. Spermatogenesis in this species must require.... (Circle ONE) mitosis
either
meiosis
4. For each cell below, write whether it is haploid (1N) or diploid (2N) and then write in
where you can find that cell within a mammal (be as specific as you can).
Cell
1N or 2N?
Location?
a. Follicle cell
_______________
_________________________________________
b. 1° spermatocyte _______________
_________________________________________
c. 2° oocyte
_______________
_________________________________________
d. mature sperm
_______________
_________________________________________
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