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Science Lab Report
Name:
Date:
Course:
Lesson:
Unit:
Modeling Meiosis Lab:
INTRODUCTION:
Meiosis is the process by which eukaryotic organisms produce egg and sperm having half the genetic information
(haploid) of the other cells in the organism’s body (diploid). You will notice some similarities to mitosis but some
definite differences in meiosis that result in genetic diversity in the gametes as well as the offspring formed by the
eventual fusion of the egg and sperm.
Two of the most noted differences in meiosis are that:
1) There are two complete divisions resulting in four daughter cells
2) Meiosis has crossing over, an event that occurs in Prophase I that increases genetic variation in the
gametes. Crossing over occurs between homologous chromosomes. These are the pairs of chromosomes in
an organism’s body that carry genes for the same trait located at identical positions on the two
chromosomes. Even though they carry the same gene they may, however, possess different alleles for the
gene which result in different forms of the trait.
PRE-LAB (3 points):
1. Label the following parts of this tetrad: centromeres, sister chromatids, homologous chromosomes.
2. What are the two elements of meiosis that add variation to our population? (Hint: one occurs in prophase I and the
other in metaphase I).
3.
Created by Mr. Erik L Albertine © 2011
Which of the chromosomes #2-5 could be homologous
with chromosome #1? Explain your answer.
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Science Lab Report
MATERIALS:
 12 chromosomes:
o 4 plastic forks – 2 of 1 color, 2 of another color
o 4 plastic knives – 2 of 1 color, 2 of another color
o 4 plastic spoons – 2 of 1 color, 2 of another color
 Cell Membrane
o Yarn/string/rope/pipe cleaners/twine
 Camera
PROCEDURE:
1. Using the thread/twine/etc., create the cell membrane for your cell. It needs to be large enough to hold all 12
pieces of silverware.
2. Begin with two forks, two knives, and two spoons (one of each from each set) inside your string cell membrane.
Proceed through each of the steps of meiosis using your flatware “chromosomes.” Use the table below and
textbook pages 324-325 for help.
3. Take pictures of Interphase, Prophase I, Metaphase I, Metaphase II and Cytokinesis II and submit them with this
report.
Phase
Modeling
Interphase
Replicate the DNA of your chromosomes by adding a second fork, knife, or spoon to each
existing fork, knife, and spoon. Hold each pair of “chromatids” together with a rubber
band (centromere).
Prophase I
Create tetrads (XX) by pairing homologous chromosomes (set them next to each other).
Model crossing over as best you can given the model we are using.
Metaphase I
Line up your tetrads along the metaphase plate. Model independent assortment.
Anaphase I
Move the homologous chromosomes to opposite ends of the cell.
Telophase I
You should have three chromosomes, knife, fork, and spoon, (each composed of two chromatids) in each of your two nuclei.
Cytokinesis I
Divide your cell membrane so that you have two daughter cells (two string circles for cells).
Prophase II
Check to make sure that each of your two cells contains three chromosomes made up of sister
chromatids.
Metaphase II
Line your chromosomes up along the middle of each of your cells.
Anaphase II
Separate your sister chromatids (remove rubber band holding them together). Move one sister
chromatid from each chromosome to opposite sides of your cell.
Telophase II
You should now have four nuclei, with three single chromosomes in each of the cells.
Cytokinesis II
Divide your cell membranes so that you have four daughter cells (use more string).
Created by Mr. Erik L Albertine © 2011
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Science Lab Report
DATA (3 Points):
Make sure to include your pictures/drawings of Interphase, Prophase I, Metaphase I, Metaphase II and Cytokinesis II
CONCLUSION (6 points): Answer each of the following using complete sentences:
1. Does mitosis more closely resemble meiosis I or meiosis II? Explain your answer.
2. What is crossing over? When does it occur during meiosis? Why did you have difficulty modeling this element
of meiosis using your “chromosomes?”
3. Think about your modeling. Visually, what is the major difference between the separation of chromosomes
between anaphase I and anaphase II
4. What is independent assortment? When does it occur during meiosis? How did you model this element of
meiosis?
5. Which part of meiosis, meiosis I or meiosis II, is responsible for reducing the chromosome number by half in the
cell?
Created by Mr. Erik L Albertine © 2011
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