Volume 7, Issue 1
The Workshop Project Newsletter
Meiosis and Gametogenesis
Joseph G. Griswold, Ph.D.
City College of New York, CUNY (retired)
Most cells in our bodies have nuclei with 46 chromosomes organized in 23
Because there are two chromosomes of each type, the cells are called
and 2N = 46.
If mothers and
fathers each passed 46 chromosomes to their offspring in reproducing, the children in the new generation
would have 92 chromosomes apiece.
In the following generation it would be 184.
Obviously, the increase
does not occur; normal people in each generation have the same 2N = 46.
To produce a new individual (a
, initially) with 46 chromosomes, an egg and sperm each
contribute half the total, or 23, when fertilization occurs.
Both sperm and eggs, called
from body cells in which the full 46 chromosomes are present.
These body cells, located in the testes and
ovaries, undergo special cell divisions, which reduce the number of chromosomes in half.
The special cell
divisions, two for each cell, make up a process called
Cells that have completed meiosis then
differentiate to become gametes.
The general objective of this laboratory is to learn how meiosis occurs in forming eggs and sperm to
carry genetic information from one generation to the next.
1. Demonstrate an understanding of the terminology of cellular genetic structure using diagrams.
2. Demonstrate the process of meiosis by using models or drawing chromosomes on cell outlines.
3. Compare the processes of mitosis and meiosis by:
a. drawing diagrams with explanations of the
processes, and b. comparing the genetic makeup in parent and daughter cells.
4. For spermatogenesis and oogenesis: a) compare and contrast
b) label diagrams of the processes;
relate the structures of the two gametes to their functions in producing a zygote.
5. Explain the processes of fertilization and cleavage using diagrams and models.
Prepare for your workshop by reading your textbook (Campbell, 4
Edition, Chapter 12;
Edition, Chapter 11) and completing the Pre-Workshop activities below.
Show your work on the pages
of this handout.
Genetics of the Cell
Do this activity with a round robin.
The following student may suggest changes to the answer made by the
Answer the following questions by referring to Fig. 10.1.
For the cell in Fig. 10.1,
How many chromosomes are represented?____ How many homologous pairs?_______
Peer-Led Team Learning: Introductory Biology, Module 10
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Joseph G. Griswold -- Progressions, V.7, No. 1,
Fall 2005 –