BIOH122 Session 26
Gametogenesis
Introduction
1.
a. Define gametogenesis.
b. What cells are gametes?
c. What are the two cell division processes that occur during the cell
cycle?
d. Define the cell cycle.
The Cell Cycle and Interphase
2.
Identify the two primary parts of the cell cycle.
3.
What’s happening during cellular interphase?
4.
Describe cellular events during G1.
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5.
Describe S phase activities.
6.
Describe how DNA replication begins during the S
phase.
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7.
Describe how new DNA strand forms and ultimately produce two identical DNA molecules.
8.
What happens during the G2 phase of interphase?
Mitotic Cell Division
9.
What is produced by the mitotic (M) phase of the cell cycle?
10.
What is the function of mitotic cell division?
11.
Define the two mitotic cell processes.
12.
What happens to cellular DNA during the four stages of mitosis?
13.
Describe events during prophase.
14.
Describe events during metaphase.
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15.
a. Describe events during anaphase.
b. Describe cytokinesis.
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16.
Describe events during telophase.
Meiotic Cell Division
17.
Meiosis is a cell division that creates “daughter cells” that are
different from the parent cell. Explain.
18.
Somatic cells are “body cells”, those other than reproductive. Contrast the chromosomes of somatic
cells and gametes.
19.
Contrast meiotic and mitotic cell divisions. How do they differ as
processes and how are their products different?
20.
Meiosis involves two cell divisions called Meiosis I and Meiosis II.
Meiosis I is mechanically similar to mitosis with two notable exceptions.
a. What is synapsis?
b. What is crossing over?
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Genetic variation created by crossing over is beneficial. It shuffles human genes in new combinations
providing variety and diversity essential to species survival.
c. Describe a meiotic difference that occurs during Metaphase I.
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21.
During interphase, the DNA has replicated so the chromosomes that appear during prophase are
actually doubled. The structure they form is called a tetrad. During mitotic anaphase, the tetrad splits
moving a copy of each homologous chromosome to each daughter cell. This produces two daughter
cells identical to each other and identical to the parent cell. This ISN’T what happens in Anaphase I of
meiosis, however. Explain.
22.
Explain why the daughter cells produced by Meiosis I are haploid?
At this point, the meiotic daughter cells contain BOTH copies of one chromosome. They are called
“sister chromatids.”
23.
Why is the chromatid activity of anaphase II similar to the activity in mitotic anaphase?
24.
Describe the chromosome complement of the meiotic
daughter cells.
Spermatogenesis
25.
a. Define spermatogenesis.
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b. Where does this process occur?
26.
a. Describe the developmental events of the spermatogonia cells.
b. If you didn’t do so above, describe development of a primary spermatocyte.
27.
Describe how two secondary spermatocytes are formed.
28.
Describe how spermatids are formed.
29.
Describe spermiogenesis.
Oogenesis
30.
a. Define oogenesis.
b. Where does the process occur?
c. When do oogonia cells develop?
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31.
Describe production of oogonia cells.
32.
What is a primordial follicle?
33.
a. Describe primary oocyte development.
b. Oogonia cells begin prophase I during fetal development. This division, however, is stopped prior to
birth. When is meiosis I completed?
34.
Following puberty, each month a primary oocyte is stimulated to complete the first meiotic
division. Describe this development.
35.
a. Describe secondary oocyte formation within a “graafian” follicle.
b. What is the function of the first polar body (you’ll have to do some thinking on this one)?
c. Describe what happens to the secondary oocyte.
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36.
a. The secondary oocyte is suspended within meiosis II. Describe the development
of these cells with and without fertilization.
b. If fertilization occurs, a second polar body is formed which then degenerates. What is the function of
the polar body? (Again, a little thought is needed.)
37.
Describe zygote formation.
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