Modeling Meiosis
Name: _________________________________
Goal: You will model the steps that take place in the sex organs of most organisms to create gametes. The goal of meiosis is to
create sex cells with only one copy of every chromosome (HAPLOID)
[No pairs: Regular cells are diploid which means that they have homologous pairs.]
Meiosis has two major steps – Meiosis I & Meiosis II. *Draw chromosomes accurately (color & size) at each stage of Meiosis.
Reminder Vocabulary:
Chromosome – A tightly wound DNA strand containing code for a set of genes.
Homologous pair – A pair of chromosomes including one from EACH parent.
Sister Chromatid – A chromosome and its copy made during replication.
Meiosis I: Imagine your desk is a cell.
1. Place 1 chromosome of each type inside
cell. You should have 6 chromosomes: 2
Long, 2 medium and 2 short (2 colors
each). Leave matching 6 chromosomes
(their sister chromatids) in bag with clips.
2. Take additional DNA/chromosomes out of
the bag and clip the sister chromatids
(identical copies) together.
3. Match the homologous pairs and line
pairs up vertically in the cell. You can line
them up in any order and with the
different colors on either side as long as
the homologous pairs are side-by-side.
The movement of the chromosomes is
actually done by protein fibers that grow
from the ends of the cell. Your fingers can
act as these fibers.
4. Protein fibers pull homologous pairs away
from each other to opposite ends of the
cell.
5. The cell splits in two cells, each with only
one member of each homologous pair. Do
your chromosome colors make sense?
This is the end of Meiosis I.
Overall, what is the main event of
this stage?
_______________________________________
_______________________________________
Meiosis II (Use string as membrane
to keep track of the new cells).
6. Chromosomes once again line up
in the center of the cells. *Pay
attention to the colors for each
set of chromosomes.
7. The Centromere separates
(place paper clips back in the
bag). Sister chromatids pull
apart to opposite ends of the cell
8. Each cell now divides into two
cells with half the number of
chromosomes of the original cell
that we started with.
This is the end of Meiosis II.
Overall what is the main event of
this stage? _____________________________________
1. Cell currently has ____ pairs of
chromosomes called _________________
________
Are they single or duplicated:
________________
This represents a cell in the ovaries or
testes ready to start meiosis. Before
meiosis begins, all DNA must be copied
(which means we need copies of each
chromosome.)
2. Each chromosome of the
homologous pair now has a
________________ ______________
3. How many different ways could you
arrange these chromosomes? ________
4. Are chromosomes pulled apart as
sister chromatids or are they still
homologous pairs? Explain
5.
a. How many chromosomes are in
each cell? __________
b. Are they single or duplicated
chromosomes? _______________
c. How many homologous pairs?
_______
6. This time ___________________
_________ line up in the center.
7. The ____________________ (paper
clip) breaks apart and _____________
______________ now separate.
8.
a. How many chromosomes
are in this cell? __________
b. Are they single or
duplicated chromosomes?
_____________________
c. How many homologous
pairs? ________
Use the four “egg cells” to answer analysis questions. Return gamete materials to the bag when finished.
1. How many total sex cells (gametes) were created by meiosis? _______
2. How does the DNA and number of chromosomes of the final sex cells compare to the DNA and number of
chromosomes of the starting cell?
3. How does the DNA information in each new sex cell compare to the other sex cells? Are they all the same or
different? Explain.
4. Look at the chromosomes in the cells of a few other groups. Are they all the same or are there differences? If
there are differences what do you think caused these differences?
5. What is the main “goal” or purpose of meiosis?
Keep ONE of the four “egg cells” intact. Return other gamete materials to the bag.
6. You successfully built egg cells. What do you think will happen to these chromosomes if the egg fuses with a
sperm cell?
7. Using a BYOD or School Device, visit learn.genetics.utah.edu/content/chromosomes . Click on “Using karyotype
to diagnose genetic disorders.”
Scan down the page to find out about one of the following genetic disorders:
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Klinefelter Syndrome (XXY)
Turner Syndrome (X)
Down Syndrome (Trisomy 21)
Cri-du-Chat Syndrome (Chromosome 5)
Williams Syndrome (Chromosome 7)
Disorder name: ____________________________________
Homologous Chromosome # altered to cause this disorder: ______________
Specifically describe what happens to the chromosome?
List one symptom of the disorder (expressed by individual):
Briefly describe one piece of information known about the disorder:
Modeling Meiosis Exit Ticket
Name
Give an example of a HOMOLOGOUS PAIR from the lab.
Modeling Meiosis Exit Ticket
Name
Give an example of a HOMOLOGOUS PAIR from the lab.
How were SISTER CHROMATIDS represented?
How were SISTER CHROMATIDS represented?
Number of Cells
Haploid or
Diploid?
Number of Cells
Haploid or
Diploid?
Start of Meiosis
Start of Meiosis
After Meiosis I
After Meiosis I
After Meiosis II
After Meiosis II
Modeling Meiosis Exit Ticket
Name
Give an example of a HOMOLOGOUS PAIR from the lab.
Modeling Meiosis Exit Ticket
Name
Give an example of a HOMOLOGOUS PAIR from the lab.
How were SISTER CHROMATIDS represented?
How were SISTER CHROMATIDS represented?
Number of Cells
Haploid or
Diploid?
Number of Cells
Start of Meiosis
Start of Meiosis
After Meiosis I
After Meiosis I
After Meiosis II
After Meiosis II
Haploid or
Diploid?