Laboratory Investigation #10
Meiosis
Description of the Lab
This lab is designed to show the students the different phases of meiosis using models
made of yarn and beads. It will incorporate similar models to show how fertilization and
Outline of Investigation
1. Major Events in Meiosis
A. 2 large sheets of poster board, compass
B. Zip-loc bags containing the following: 2 four inch pieces of red yarn, 2
four inch pieces of blue yarn, 2 two inch pieces of red yarn, 2 two inch
2. Function of Meiosis and Fertilization in Generating Genetic Variability
A. Use 8 dark and 8 light beads from the zip-loc bag; poster board with
3. Visualizing Meiosis
A. Use yarn and beads from the zip-loc bag; poster board with appropriate
circles
Laboratory Materials and Equipment for Student Use
Materials and Equipment
Per
Student
Per Pair of
Students
Per Lab
Group
Per
Room
Poster board
2
30
Compass
1
15
Zip loc bags, sandwich size
1
15
Preparation of laboratory Materials and Reagents
1 day prior to the lab
1. Cut the pieces of yarn and clear straw or tape to fill 15 sandwich size zip-loc
bags with the needed supplies for each lab pair. In the zip-loc bag, put 1 four inch red
Questions for Lab #10 Meiosis
Use the knowledge you acquired in this lab exercise, along with information from your
textbook, to answer the following questions.
1. What are the three major events in meiosis? Of those three, which are unique to
meiosis and which are shared with the process of mitosis?
Four inch pieces of red yarn
2
30
Four inch pieces of blue yarn
2
30
Two inch pieces of red yarn
2
30
Two inch pieces of blue yarn
2
30
6 x 9 mm dark blue beads
8
90
6 x 9 mm light blue beads
8
90
6 x 9 mm red beads
8
90
6 x 9 mm pink beads
8
90
1.5 cm pieces of a clear straw OR
4
60
Clear tape
1
15
2. Based on your yarn model for meiosis with diploid chromosome number of 4, how
many different combinations of non-homologous chromosomes are possible in the
gametes from a single mitotic event?
Gametes are not formed from mitotic events.
How many different combinations would be possible from multiple mitotic events, again
for a diploid number of 4?
Gametes are not formed from mitotic events.
What step in meiosis accounts for the different combinations of non-homologous
chromosomes in the gametes?
3. Consider the following: Different alleles (R and r) for flower color reside on one pair
of homologous chromosomes. Different alleles (H and h) for hairy leaves reside on a
second pair of homologous chromosomes. Write the different combinations of alleles
that are possible in the gametes. Remember that each gamete can only have one allele for
each genetic trait. If you have trouble visualizing this, try working through using
diagrams “Major steps in Meiosis”.
4. Different combinations of alleles for two traits are possible when genes reside on non-
homologous chromosomes. Are different combinations of alleles possible for genes that
reside on the same homologous chromosome? Explain.
5. Sometimes, mistakes arise in meiosis and the homologous chromosomes do not
separate from one another. Chromatids do, however, separate How many gametes and
how many sets of chromosomes will be produced in this situation?
Four gametes would still be formed but the gametes would have the correct number
6. Assume that these gametes are fertilized by normal gametes. How many sets of
chromosomes will be present in the zygote produced by this fertilization event?