Your full name: 102/103 lab 5: meiosis instructions: and 3425

Your Full Name:

102/103
Lab 5: Meiosis
INSTRUCTIONS:

and submit it via the Assignments Folder by the date listed in the Course
Schedule (under Syllabus).

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Course Content. Read the introduction and the directions for each exercise/experiment
carefully before completing the exercises/experiments and answering the questions.

Save your Lab 5 Answer Sheet in the following format: LastName_Lab5 (e.g.,
Smith_Lab5).

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Pre-Lab Questions
1. Compare and contrast mitosis and meiosis.

2. What major event occurs during interphase?

Experiment 1: Following Chromosomal DNA Movement
through Meiosis
Data Tables and Post-Lab Assessment
Trial 1 – Meiotic Division Beads Diagram:
Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase I

Cytokinesis

Trial 2 – Meiotic Division Beads Diagram:
Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase I

Cytokinesis

Post-Lab Questions
1. What is the ploidy of the DNA at the end of meiosis I? What about at the end of meiosis

II?

2. How are meiosis I and meiosis II different?

3. Why do you use non-sister chromatids to demonstrate crossing over?

4. What combinations of alleles could result from a crossover between BD and bd

chromosomes?

5. How many chromosomes were present when meiosis I started?

6. How many nuclei are present at the end of meiosis II? How many chromosomes are in

each?

7. Identify two ways that meiosis contributes to genetic recombination.

8. Why is it necessary to reduce the number of chromosomes in gametes, but not in other

cells?

9. Blue whales have 44 chromosomes in every cell. Determine how many chromosomes

you would expect to find in the following:

a.i.

Sperm Cell:

a.ii.

Egg Cell:

a.iii.

Daughter Cell from Mitosis:

a.iv.

Daughter Cell from Meiosis II:

10. Research and find a disease that is caused by chromosomal mutations. When does the

mutation occur? What chromosomes are affected? What are the consequences?

11. Diagram what would happen if sexual reproduction took place for four generations using

diploid (2n) cells.

Experiment 2: The Importance of Cell Cycle Control
Data Tables and Post-Lab Assessment
1.

Post-Lab Questions
1. Record your hypothesis from Step 1 in the Procedure section here.

2. What do your results indicate about cell cycle control?

3. Suppose a person developed a mutation in a somatic cell which diminishes the

performance of the body’s natural cell cycle control proteins. This mutation resulted in
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cancer, but was effectively treated with a cocktail of cancer-fighting techniques. Is it possible
for this person’s future children to inherit this cancer-causing mutation? Be specific when
you explain why or why not.

4. Why do cells which lack cell cycle control exhibit karyotypes which look physically

different than cells with normal cell cycle.

5. What are HeLa cells? Why are HeLa cells appropriate for this experiment?

Experiment 1:
Following
Chromosomal DNA
Movement through
Meiosis
In this experiment, you
will model the movement
of the chromosomes
through meiosis I and II to
create gametes.

Materials

2 Sets of Different Colored Pop-it® Beads (32 of e
may be any color)
8 5-Holed Pop-it® Beads (used as centromeres)
Procedure:
Part 1: Modeling Meiosis
without Crossing Over
As prophase I begins, the
replicated chromosomes
coil and condense…
1.

Build a pair of
replicated,
homologous
chromosomes. 10
beads should be
used to create each
individual sister
chromatid (20
beads per
chromosome pair).
Two five-holed
beads represent
each centromere.
To do this…

Figure 3: Bead set-up. The blue beads
represent one pair of sister chromatids
and the black beads represent a second
pair of sister chromatids. The black and
blue pair are homologous.
a.

Start with
20 beads of
the same
color to
create your
first sister
chromatid
pair. Five
beads must
be snapped
together for
each of the
four
different
strands.
Two
strands
create the
first
chromatid,
and two
strands
create the
second
chromatid
with a 5holed bead
at the
center of
each
chromatid.
This creates
an “I”
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shape.
b.

Connect the
“I” shaped
sister
chromatids
by the 5holed beads
to create
an “X”
shape.

Repeat this
process
using 20
new beads
(of a
different
color) to
create the
second
sister
chromatid
pair.

Assemble a second
pair of replicated
sister chromatids;
this time using 12
beads, instead of
20, per pair (six
beads per each
complete sister
chromatid strand).

CROSSING
OVER IN THIS
TRIAL. You will
simulate crossing
over in Part 2.
4.

Configure the
chromosomes as
they would appear
in each of the
stages of meiotic
division (prophase
I and II, metaphase
I and II, anaphase I
and II, telophase I
and II, and
cytokinesis).

Diagram the
corresponding
images for each
stage in the
sections titled
“Trial 1 – Meiotic
Division Beads
Diagram”. Be sure
to indicate the
number of
chromosomes
present in each cell
for each phase.

Figure 4: Second set of replicated
chromosomes.
6.

Disassemble the
beads used in Part
1. You will need to
recycle these beads
for a second
meiosis trial in
Steps 8 – 13.

Part 1 – Meiotic Division
Beads Diagram
Prophase I
Metaphase I
Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II

Telophase II
Cytokinesis
Part 2: Modeling Meiosis
with Crossing Over
7.

Start with
20 beads of
the same
color to
create your
first sister
chromatid
pair. Five
beads must
be snapped
together for
each of the
four
different
strands.
Two

strands
create the
first
chromatid,
and two
strands
create the
second
chromatid
with a 5holed bead
at the
center of
each
chromatid.
This creates
an “I”
shape.
b.

Connect the
“I” shaped
sister
chromatids
by the 5holed beads
to create
an “X”
shape.

Repeat this
process
using 20
new beads
(of a
different
color) to
create the
second
sister
chromatid
© eScience Labs, LLC 2014

pair.
8.

Assemble a second
pair of replicated
sister chromatids;
this time using 12
beads, instead of
20, per pair (six
beads per each
complete sister
chromatid strand).
Snap each of the
four pieces into a
new five-holed
bead to complete
the set up.

Pair up the
homologous
chromosomes
created in Step 8
and 9.

10.

SIMULATE
CROSSING
OVER. To do this,
bring the two
homologous pairs
of sister
chromatids
together (creating
the chiasma) and
exchange an equal
number of beads
between the two.
This will result in
chromatids of the
same original
length, there will
now be new

combinations of
chromatid colors.
11.

Configure the
chromosomes as
they would appear
in each of the
stages of meiotic
division (prophase
I and II, metaphase
I and II, anaphase I
and II, telophase I
and II, and
cytokinesis).

12.

Diagram the
corresponding
images for each
stage in the section
titled “Trial 2 Meiotic Division
Beads Diagram”.
Be sure to indicate
the number of
chromosomes
present in each cell
for each phase.
Also, indicate how
the crossing over
affected the genetic
content in the
gametes from Part1
versus Part 2.

Part 2 – Meiotic Division
Beads Diagram:
Prophase I
Metaphase I

Anaphase I
Telophase I
Prophase II
Metaphase II
Anaphase II
Telophase II
Cytokinesi

Experiment 2: The Importance of Cell Cycle Control
Some environmental factors can cause genetic mutations which result in a
lack of proper cell cycle control (mitosis). When this happens, the possibility
for uncontrolled cell growth occurs. In some instances, uncontrolled growth
can lead to tumors, which are often associated with cancer, or other biological
diseases.
In this experiment, you will review some of the karyotypic differences which
can be observed when comparing normal, controlled cell growth and
abnormal, uncontrolled cell growth. A karyotype is an image of the complete
set of diploid chromosomes in a single cell.
Procedure
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Materials
*Computer Access
*Internet Access

*You Must Provide

Begin by constructing a hypothesis to explain what differences you
might observe when comparing the karyotypes of human cells which
experience normal cell cycle control versus cancerous cells (which
experience abnormal, or a lack of, cell cycle control). Record your
hypothesis in Post-Lab Question 1.
Note: Be sure to include what you expect to observe, and why you think
you will observe these features. Think about what you know about
cancerous cell growth to help construct this information

Go online to find some images of abnormal karyotypes, and normal
karyotypes. The best results will come from search terms such as
“abnormal karyotype”, “HeLa cells”, “normal karyotype”, “abnormal
chromosomes”, etc. Be sure to use dependable resources which have
been peer-reviewed

Identify at least five abnormalities in the abnormal images. Then, list and
draw each image in the Data section at the end of this experiment. Do
these abnormalities agree with your original hypothesis?
Hint: It may be helpful to count the number of chromosomes, count the
number of pairs, compare the sizes of homologous chromosomes, look
for any missing or additional genetic markers/flags, etc.

Data
1.
2.
3.

4.
5.
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Your full name: 102/103 lab 5: meiosis instructions: and 3425

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