Meiosis Unit Student Design Cover Page
(see guidelines on page 10)
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Meiosis Unit Front Page
At the end of this unit, I will:

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Know the difference between sexual and asexual reproduction.
Understand the difference between haploid and diploid cells.
Understand the steps involved in meiosis with regard to gametes and
chromosome number.
Interpret a karyotype, being able to identify gender or potential disorder from
the karyotype.
Roots, Prefixes and Suffixes I will be able to understand when I see them in words are:


Homo-, chromo-, hap-, di-, karyo-logous, -some
The terms I can completely define are:

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Gene, homologous chromosome, gamete, haploid, fertilization, diploid,
meiosis, crossing over
Karyotype, telomere, nondisjunction
The assignments I will have completed by the end of this unit are:
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Meiosis Unit Cover Page
Meiosis unit notes
Completed the “Using Karyotypes to Predict Genetic Disorders” web activity
Completed the “Patient Histories” web activity
Acted out Meiosis using pipe cleaners as chromosomes
Memorized and sung the Meiosis Square Dance for Extra Credit
Completed the Meiosis Review Worksheet
Meiosis Unit Backpage
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Meiosis and Reproduction Notes
Warm-up:
Humans have 46 chromosomes in all of their body cells. The first cell of the organism is made by joining
egg and sperm.
1. How many chromosomes in a human egg or sperm cell? Explain.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
2. Can cell division by mitosis (duplication of cells) produce egg or sperm? Explain.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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Meiosis and Sexual Reproduction:
Asexual Reproduction
What is Asexual Reproduction?
Called _________________ reproduction in plants
•
A form of duplication using only ____________.
–
Example: _________________________
_________________________________
What are the limitations of
asexual reproduction?
Produces only genetically ___________________ offspring since all
divisions are by mitosis.
•
Offspring called
meaning that each is an
exact copy of the original organism
•
This method of reproduction is __________ and effective
allowing the spread of an organism
–
•
Example: _________________________
Since the offspring are identical, there is no mechanism for
introducing
•
What are some specific
examples of asexual
reproduction?
______ .
In prokaryotes and some one-celled eukaryotes, cells undergo
____________ _____________
•
Hydra reproduce by _______________
•
Planaria reproduce by ____________________
•
Several plants reproduce through _______________
reproduction.
–
Most of these organisms can reproduce
_______________ as well.
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Understanding haploid and diploid
If N=2, 2N would look like:
= A chromosome
= A chromosome
There are 2 different types of chromosomes
in this cell. 2N means that this cell is diploid
(or there are two copies of each
chromosome). How many total
chromosomes are present in this cell? _____
1. Draw the chromosomes in a diploid cell of an organism where N=3.
2. How many combinations of haploid (eggs or sperm) cells are possible if N=2? Draw the possible
combinations.
3. How many combinations of haploid cells are possible if N=3?
Draw the possible combinations.
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Sexual Reproduction
Why do organisms have sex?
Sexual reproduction increases ______________ by producing new
______________ combinations.
What does sexual reproduction
consist of?
1. ______________: Formation of two haploid sex cells (or
_______________).
•
Meiosis is a process to convert a ________ cell to a
________ gamete, and cause a change in the genetic
information to increase diversity in the offspring.
•
In humans, meiosis only occurs in the ___________
–
Spermatogenesis: In the ___________ (in males)
–
Oogenesis: In the _________________ (in females)
2. Fertilization: Combination of genetic information from two
separate cells that have one ________ the original genetic
information.
Where do gametes come from?
•
______________ for fertilization usually come from separate
parents
•
o
Female produces an ___________
o
Male produces _____________
Both gametes are haploid (1__), with a single set of
____________________ .
What are is the ploidy levels of
gametes?
•
The new individual is called a _____________, with two sets of
chromosomes (____________ or 2___).
•
Once the zygote begins to divide, it is called an
_________________.
What is the name for the process
in which two gametes combine?
_________________________
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What is the name for the way these chromosomes are organized? ___________________
Circle the sex chromosomes. What is the gender of this person? ____________________
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Chromosomes and Karyotypes
How many chromosomes do
humans have?
Humans have ______ chromosomes.
What are some characteristics of
chromosomes?
•
There is a __________ set for humans; __n = 46
•
There are two types:
1. ______________ (#1 – 22)
2. _______ Chromosomes (#____)
What are some characteristics of
autosomes?
•
______________ chromosomes
•
Humans have _____ sets of 2.
o
What are some characteristics of
sex chromosomes?
What can Chromosomes tell us?
One from each parent
•
Humans have 1 set of ____.
•
Female sex chromosomes are ___________________ (X__)
•
Male sex chromosomes are _____________________(X__)
Scientists can organize chromosomes in a cell into a
________________.
In a karyotype, chromosomes are arranged in order of:
1. _____________
2. _____________ _________________
3. ___________________ ______________
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Meiosis is often called
/
Meiosis can be broken up into two phases:
and
.
Meiosis I:
Prophase I is much like the prophase of mitosis:
1. ______________________________________________
2. ___________________________________________
____________________________________________
3. ___________________________________________
_____________________________________________
However, unlike mitosis, where the chromosomes of a
homologous pair are randomly scattered within the nucleus, in
meiosis, 1. ________________________________________
_______________________________________________________
2. ___________________________________________________________________________
_____________________________________________________________________________
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Metaphase I
Anaphase I
Telophase I
Metaphase I:
align at the metaphase plate.
Microtubules are attached to the
.
Anaphase I: Homologous pairs separate with
together.
remaining
Telophase I: Two daughter cells are formed with each daughter containing only one
of the homologous pair.
Each daughter cell is now
.
Meiosis II:
formation
Prophase II:
does not replicate, this is just like mitotic prophase.
Metaphase II: Chromosomes align at the
Anaphase II:
pole.
Telophase II: Cell division is complete.
obtained.
divide and sister chromatids migrate separately to each
daughter cells are
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USING KARYOTYPES TO PREDICT GENETIC DISORDERS
Use the following website to help you fill in the blanks and answer the following
questions. http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/
1.
A normal human karyotype has ______ chromosomes: _____ pairs of autosomes and ____ sex
chromosomes. Cells don’t always end up with these chromosomal numbers, though. The following
text outlines what happens when cells end up with too much or too little genetic information.
2.
Too many or too few chromosomes
a.
To understand how our cells might end up with too many or too few chromosomes, we need
to know how the cells normally get _____ chromosomes.
b.
First we need to understand meiosis. Meiosis is the cell division process that produces egg
and sperm cells (___________), which normally have ______ chromosomes each.
c.
If eggs and sperm only have one set of _____________________, then how do we end up
with 46 chromosomes? During ______________________, when the egg and sperm fuse,
the resulting _________________ has two copies of each chromosome needed for proper
development, for a total of ________.
3.
How can cells end up with too many or too few chromosomes?
a.
Sometimes chromosomes are incorrectly distributed into the egg or sperm cells during
_______________. When this happens, one cell may get __________ copies of a particular
chromosome, while another cell gets none.
b.
What happens if a sperm or egg cell with an abnormal number of chromosomes participates
in fertilization? It depends on how many chromosomes the gamete has. For example, if a
___________ with an extra chromosome fertilizes an egg with a normal chromosome number,
the resulting zygote will have _____ copies of one chromosome. This is called
_______________.
c.
If a sperm that is missing a ___________________ fertilizes an egg, then the resulting zygote
will have only one copy of that chromosome. This is called ________________________
d.
People who are born with an abnormal number of chromosomes often have genetic disorders
because their cells contain too much or too little genetic information. Scientists can predict
genetic disorders by looking for extra or missing chromosomes in a ___________________.
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4.
Missing pieces of chromosomes
a.
In some cases, genetic material is missing from a chromosome. Such chromosomes are said
to have __________________.
b.
Deletions large enough to be seen in a karyotype result in the loss of many _____________.
In humans, these are less comman than deletions that remove small portions of a
chromosome.
c.
A _________________________ is a chromosome rearrangement in which part of a
chromosome breaks off and then reattaches to a different chromosome.
QUIZ: Use the options listed below and your knowledge to answer the following questions. Some options will
be used more than once.
Normal female
Turner Syndrome
Normal male
Klinefelter Syndrome
Down Syndrome
1. _______________________
5. _______________________
2. _______________________
6. _______________________
3. _______________________
7. _______________________
4. _______________________
8. _______________________
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Patient Histories: Karyotyping Activity
Introduction
This exercise is a simulation of human karyotyping using digital images of
chromosomes from actual human genetic studies. You will be arranging chromosomes
into a completed karyotype, and interpreting your findings just as if you were working in
a genetic analysis program at a hospital or clinic. Karyotype analyses are performed
over 400,000 times per year in the U.S. and Canada. Imagine that you were performing
these analyses for real people, and that your conclusions would drastically affect their
lives.
G Banding
During mitosis, the 23 pairs of human chromosomes condense and are visible with a
light microscope. A karyotype analysis usually involves blocking cells in mitosis and
staining the condensed chromosomes with Giemsa dye. The dye stains regions of
chromosomes that are rich in the base pairs Adenine (A) and Thymine (T) producing a
dark band. A common misconception is that bands represent single genes, but in fact
the thinnest bands contain over a million base pairs and potentially hundreds of genes.
For example, the size of one small band is about equal to the entire genetic information
for one bacterium.
The analysis involves comparing chromosomes for their length, the placement of
centromeres (areas where the two chromatids are joined), and the location and sizes of
G-bands.
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Your assignment
This exercise is designed as an introduction to genetic studies on humans. Karyotyping
is one of many techniques that allow us to look for several thousand possible genetic
diseases in humans.
You will evaluate 3 patients' case histories, complete their karyotypes, and diagnose
any missing or extra chromosomes. The assignment will be completed online, while the
questions must be answered on the following page.
Use the following website to help these patients diagnose their disorders from
karyotypes and answer the following questions.
http://www.biology.arizona.edu/human_bio/activities/karyotyping/karyotyping2.html
Patient Histories
Patient A
Patient A is the nearly-full-term fetus of a forty year old female. Chromosomes were
obtained from fetal epithelial cells acquired through amniocentesis. Complete Patient
A's Karyotype (this will have to be done online).
Patient B
Patient B is a 28 year old male who is trying to identify a cause for his infertility.
Chromosomes were obtained from nucleated cells in the patient's blood. Complete
Patient B's Karyotype.
Patient C
Patient C died shortly after birth, with a multitude of anomalies, including polydactyly
(more than five fingers on a hand) and a cleft lip. Chromosomes were obtained from a
tissue sample. Complete Patient C's Karyotype.
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Making a diagnosis
The next step is to either diagnose or rule out a chromosomal abnormality. In a patient
with a normal number of chromosomes, each pair will have only two chromosomes.
Having an extra or missing chromosome usually renders a fetus inviable (meaning that
it will not live). In cases where the fetus makes it to term, there are unique clinical
features depending on which chromosome is affected. Listed below are some
syndromes caused by an abnormal number of chromosomes.
Diagnosis
Chromosomal Abnormality
Normal # of chromosomes
patient's problems are due to something other than an
abnormal number of chromosomes.
Klinefelter's Syndrome
one or more extra sex chromosomes (i.e., XXY)
Down's Syndrome
Trisomy 21, extra chromosome 21
Trisomy 13 Syndrome
extra chromosome 13
1. What observations can you make regarding patient A’s karyotype?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
2. What diagnosis would you give patient A? Explain your answer.
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
3. What observations can you make regarding patient B’s karyotype?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
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4. What diagnosis would you give patient B? Explain your answer.
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
5. What observations can you make regarding patient C’s karyotype?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
6. What diagnosis would you give patient C? Explain your answer.
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
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Meiosis Pipe Cleaner Play
Introduction: A fruit fly’s testes are going through meiosis. What combination of alleles will be
passed on in each of his gametes?
Act 1: Scene 1 - Interphase
a.
The fruit fly has 6 chromosomes. The genotype of your fruit fly is GgBbrr. Remove
these chromosomes from your bag to start the play.
-Chromosome 1: with allele G (for Gray eyes)
-Chromosome 2: with allele g (for green eyes)
-Chromosome 3: with allele B (for black, solid body)
-Chromosome 4: with allele b (for striped body)
-Chromosome 5: with allele r (for shriveled wings)
-Chromosome 6: with allele r (for shriveled wings)
b.
c.
During S-phase of interphase, DNA duplication. (Exact size, color, and alleles,
connecting at the centromere)
Draw the arrangement of your chromosomes at this phase. Make sure to mark the
alleles.
Act 1: Scene 2 - Prophase I
a. Homologous chromosomes pair up (not line up)
b. Cross-over occurs on at least 2 homologous pair with at least 2 alleles. (Switch
beads)
c. Draw the new genetic combinations of your chromosomes at this phase after crossover.
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Act 1: Scene 3- Metaphase I
a. Random line-up of homologous pairs.
Act 1: Scene 4 – Anaphase I ,Telophase I, and Cytokinesis
a. Homologous pairs separate
b. Nuclei reform in two separate cells.
c. Draw the chromosomes and alleles that exist in each of the two cells.
Act 2: Scene 1 and 2 – Prophase II and Metaphase II
a. Nuclei disappear
b. Chromosomes line up at equator.
Act 2: Scene 3 and 4 – Anapahse II ,Telophase II, and Cytokinesis
a. Sister chromatids split to opposite poles
b. Nuclei reform in 4 separate cells (4 haploid gametes are created)
c. Draw the allele combination present in each of the haploid gametes.
Act 3: Fertilization
Your fly meets a female fly, and they like each other and want to have baby flies.
Choose one of your four gametes to be the “sperm”
Draw what kind of fly would be created if your fly’s sperm fertilized an egg in the other fly with
the allele combination Gbr.
Encore!
Return all pipe-cleaners into the original bag!
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Act 1: Scene I – Interphase
Act 1: Scene 2 – Prophase I
Act 1: Scene 4 –After
Cytokinesis of Meiosis I
Act 2: Scenes 3 and 4 – After
Cytokinesis of Meiosis II
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Fertilization
Choose one of the four gametes created and write down its Genotype here __________.
Have it fertilize another gamete with the genotype Gbr.
What is the new offsprings full genotype? _________________
Draw the new fly offspring in the space below. Use color and make sure it matches the genotype.
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Meiosis Square Dance Lyrics
Now coil up, coil up, coil up tight
With a fiber stuck to your centromere
If were to do meiosis right
You’re pulled into the center here
Interphase one is almost done
On the central plate for metaphase two
Marks the start of prophase one
Just like before it’s déjà vu
Face your partners and do them bow
At Interphase one you duplicate
Do-se-do crossover now
So now that you can separate
Allemande left with your left hand
The fibers tugging this is it
Promenade around the land
Time for your chromatids to split
Now grab your partner’s chromatid
Anaphase, anaphase, anaphase two
Crossing arms you’ll be glad you did
This time you wave goodbye to you
The nuclear membrane breaks down here
At telophase two half the teams on hand
Attach your fiber to you centromere
You’re feeling sad you’re a single strand
The fibers pull the dance is done
Now this is just your normal state
Hold on tight its metaphase one
With some luck you’ll procreate
Couples move to the central plate
So rest a while and unwind too
It’s anaphase one so you separate
As the nuclear membrane surrounds you
Now wave goodbye to reach your goal
Now meiosis is complete
Each partner move to the other pole
Four nuclei from ones the treat
Telophase one is mighty sad
The cytoplasm will divide
You’re all alone lost what you had
Four gametes form with you inside
Together we’ll no longer be
And if we zoom out you will find
These parts of you will be dear to me
Many more of the same kind
Prophase, prophase, prophase two
And if you’re wondering what’s the use
The spindles coming after you
It’s all so we can reproduce… reproduce
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Meiosis Review
1. What terms are used to describe cells containing the normal number of chromosomes?
________________________________________
2. What terms are used to describe cells containing half the number of chromosomes?
________________________________________
3. Mitosis produces (circle one)
diploid / haploid
cells.
4. Meiosis produces (circle one)
diploid / haploid
cells.
5. How many pairs of chromosomes do human body cells have? _______ pairs.
Chromosome Numbers of Some Common Organisms
Organism
Body cell (2n)
Gamete (n)
Human
46
_______
Garden Pea
_______
7
Fruit Fly
8
_______
Tomato
_______
12
Dog
78
_______
Chimpanzee
_______
24
Leopard Frog
26
_______
Corn
_______
10
Apple
_______
17
Indian Fern
1260
_______
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Meiosis I (Prophase I, Metaphase I, Anaphase I, Telophase I)
During prophase I, the _______________________ coil up and the _____________ fibers form. Then
each pair of homologous chromosomes come together to form a four-part structure called a
____________ (tetra = what number?____). A tetrad consists of two homologous chromosomes, each
made up of two sister chromatids.
These 4 chromatids in a ____________ are held very close and tightly together. In fact, they are so close
that the arms of non-sister chromatids can wind and twist around each other, and exchange genetic
information (genes, DNA). This is called _______________ ____________. Crossing over results in new
combinations of alleles.
The Phases of MEIOSIS
Before meiosis begins: Interphase
Before meiosis begins, what must happen to the cell’s DNA/chromosomes?
_____________________________________________
Meiosis occurs in sexual reproduction when 1 diploid germ cell produces 4 haploid cells that can mature
to become ____________________ (sperm or ova).
Prophase I
Like prophase of mitosis:
1. The ______________ ______________ disappears.
2. ___________________ move to the opposite poles and the
_______________ ___________ form between the centrioles.
3. __________________ condenses into sister _________________.
Unlike prophase of mitosis:
1. Pairs of homologous chromosomes form _________.
2. _________________ _________ may occur.
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Metaphase I
1. Spindle fibers attach to _________________.
2. Tetrads line up at the ___________________ plate.
Anaphase I
1. Tetrads, which consist of two ___________________
________________, separate.
Telophase I / Cytokinesis I
1. _______________ __________________ reappears.
2. _______________ ______________ disappears.
3. ___________________, the division of the cytoplasm and the
organelles begins and ends forming two cells.
Meiosis II (Prophase II, Metaphase II, Anaphase II, Telophase II)
The purpose of meiosis II is to separate _______________ ___________________ of each chromosome
into separate cells.
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Prophase II
1. _______________ _______________ disappears.
2. _______________ _____________ form.
3. __________________ condenses into sister _________________.
Metaphase II
1. Sister chromatids attach to the ________________
________________.
2. Sister chromatids line up at the ________________.
Anaphase II
1. Sister chromatids separate into
_____________________.
2. Chromosomes move to the opposite ___________.
Telophase II
1. ______________ _________________ reforms.
2. 4 ______________ are formed.
Quick Review
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Meiosis Unit Student Concept Map
(see guidelines on page 10)
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Meiosis Unit Back Page
The California State Standards I have come to use and understand are:
(Please check all that you do feel you used and understood this unit)

Meiosis is an early step in sexual reproduction in which the pairs of
chromosomes separate and segregate randomly during cell division to
produce gametes containing one chromosome of each type.

Only certain cells in a multicellular organism undergo meiosis.

New combinations of alleles may be generated in a zygote through the
fusion of male and female gametes.

Why approximately half of an individual’s DNA sequence comes from each
parent.

The role of chromosomes in determining an individual’s sex.

The genetic basis for Mendel’s laws of segregation and independent
assortment.
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