Download Pipe Cleaner Babies - Helena High School

Pipe Cleaner Babies-Directions
In this activity you will play the role of a parent, your lab partner will play the role of the
other parent. Use chromosome and gene models to create four offspring and determine
their genotypes and phenotypes. Then mathematically, you will determine the probability
of having offspring with different traits.
Directions
You will receive a baggie with pipe cleaners and beads. The pipe cleaners represent chromosomes and the beads
represent alleles located on the chromosomes. In humans, there are 23 pairs of chromosomes and 20,000 to 30,000
genes. For this exercise, we will only focus on a few. The non-sex chromosomes are called autosomes and the
chromosomes that determine sex are on the sex chromosomes. The baggie contains 6 chromosomes with traits for eye
color, hair color, sex and hemophilia. The hemophilia is located on the sex chromosome.
Without opening the bag, notice that you have four white and two colored pipe cleaners. If you have two pink (or red)
chromosomes, you are to play the role of female (XX). If you have one pink and one blue, you are to play the role of the
male (XY). When you are finished put the pipe cleaners back into the baggie they came in.
PROCEDURE
1. Determine the parent’s traits. Remove the chromosomes from the bag, but make sure you do NOT mix up you and
your partner's chromosomes. Arrange the chromosomes in order of size, you should have two long white pipe cleaners,
two shorter pipe cleaners, and the two colored pipe cleaners.
KEY
The white pairs represent HOMOLOGOUS
CHROMOSOMES.
The colored pairs represent SEX CHROMOSOMES
Eye Color (longer white pipe cleaners)
Brown bead represents the dominant gene - brown eyes
Blue bead represents the recessive gene - blue eyes
BB = brown eyes | Bb = brown eyes | bb = blue eyes
Hair Color (shorter white pipe cleaners)
The red bead represents the dominant gene- dark hair
The ivory bead represents the recessive gene - blonde hair
DD= dark hair | Dd = dark hair | dd = blonde hair
Hemophilia (sex chromosomes, colored pipe cleaners)
*The purple bead represents the dominant gene -- normal
*The clear bead represents the recessive gene – hemophiliac
*In girls: XHXH = normal | XHXh = normal (carrier) | XhXh = hemophiliac
*In boys: XHY = normal | XhY = hemophiliac
Time to Start Your Family
Assign one person to play mom and one to play dad
Step 1: Set up chromosomes. Place the chromosomes in order of picture above for both male bag and female bag
Step 2: Determine Sex of baby
The individual playing mom should place both pink (or red) chromosomes in separate hands behind their
back. The individual playing dad should choose the left for the right hand. Lay this chromosome in the center of
the table. This is the chromosome inherited from mom.
The individual playing dad should place the pink (or red) and the blue chromosome in separate hands
behind their back. The individual playing mom should choose a hand. Lay this chromosome in the center of the
table. This chromosome is the one inherited from dad.
*Use the key from page one to denote the genotype of the sex and the hemophilia status.
Step 3: Determine eye color
* Repeat the above steps only use the long white pipe cleaner which represents the chromosome with the
alleles for eye color.
*Record the genotype and phenotype for this child
Step 4: Determine hair color
*Repeat the above steps only use the short white pipe cleaners with represents the chromosome with the
alleles for hair color.
*Record the genotype and phenotype for the child
Step 5: Separate the chromosomes back to their original position and repeat steps 1 through 2 until you have three
children.
Step 6: Record the predicted or expected results on the lower portion of the data table based on what probabilities
the Punnett square shows for each trait.
Pipe Cleaner Babies Analysis
Name
1. What do the pipe cleaners represent?
2. What do the beads represent?
3. How many pairs of chromosomes do humans have?
4. What are autosomes?
5. What are the sex-chromosomes?
6. If you have two pink pipe cleaners which role are you playing?
7. The blue pipe cleaner represents which chromosome?
8. What do the brown beads represent?
What do blue beads represent?
What type of
phenotype is present if you have a brown bead (B) and a blue bead (b)
what genotype?
Phenotypes and genotypes of Parents
1.
2.
3.
4.
5.
6.
7.
What is mom’s genotype and phenotype for eye color?
What is dad’s genotype and phenotype for eye color?
What is mom’s genotype and phenotype for hair color?
What is dad’s genotype and phenotype for hair color?
What is mom’s genotype and phenotype for hemophilia?
Is mom a carrier for hemophilia?
What is dad’s genotype and phenotype for hemophilia?
Punnett Squares
genotypes
Eye Color
Complete the Punnett square (possibilities) for each of the following using mom and dad’s
Hair Color
Hemophilia
Punnett Square Analysis
1. What is the phenotypic ratio for blue eyes and brown eyes from this cross?
2. What is the phenotypic ratio for dark hair and blonde hair in this cross?
3. What is the phenotypic ratio for girls for hemophilia and carriers?
4. What is the phenotypic ratio for boys for hemophilia? Can males be carriers of hemophilia? Explain.
Results of Pipe Cleaner Babies
Child
Genotype
of Sex and
hemophilis
Girl or boy
(phenotype)
Phenotype of
hemophilia
(use key)
Genotype of
Eye color
Phenotype
of Eye color
Genotype
of Hair
Color
Phenotype
of hair
color
Child
1
Child
2
Child
3
Ratios: Predicted (expected) from Punnett Squares and Actual Class ratios
Trait
Blue Eye color
Brown Eye Color
Dark Hair
Blonde Hair
Sex
Girls with hemophilia
Girls – carriers
Boys with hemophilia
Predicted or
expected
Actual Class
Data
1.
Do the predicted/expected ratios match the
actual data? Use data in your answer
2.
Why would there be a difference between
predicted and actual data?
3. Explain why women are carriers for the disease hemophilia. Why do their sons, but not their daughters get the
disease? Explain and draw a picture of mother’s X chromosomes as a carrier and son with hemophilia.
4. Describe the difference between how normal traits are inherited and how sex-linked traits are inherited.
5. Notice on the data table that no female has the disease hemophilia. Explain why.
6. If you knew you were a carrier for hemophilia (or your wife was), would you choose to have children. Explain your
reasons. If you could choose the gender of the offspring which gender would you choose and would this change your
decision? Explain.
7. Other sex-linked genes found on the X chromosome include Duchenne’s muscular dystrophy (DMD), Colorblindness,
male pattern baldness. Would boys or girls be expected to inherit this condition? What conditions would need to be
required for a girl to be colorblind? Show the Punnett square.
Pipe Cleaner Babies - Teacher's Guide
Preparation Required:
Create a set of baggies for the class, using pipecleaners and beads. You'll need lots of white pipe cleaners to represent the
autosomes, then pink and blue to match the sex chromosomes. Bead colors can vary, though I tried to get them to match
the trait. It's a little work to put together, but I use the same bags year after year. You can mix and match beads by what
you can find in the store. I had trouble finding brown beads, which I would have preferred to use for the eye genes
(instead of blue and grey). I store the pipe cleaners in plastic ziplock bags to be used the next year. ALTERNATIVE ON
LAST PAGE TO PIPE CLEANERS
Each male bag will have
1 shorter white chromosome -- ivory
bead (blonde hair recessive)
1 shorter white chromosome -- red
bead (dark hair dominant)
1 Long white chromosome -- blue
bead (blue eye recessive)
1 Long white chromosome -- brown
bead (brown eye dominant)
1 pink chromosome (pipecleaner)-purple bead (normal blood)
1 blue chromosome (pipecleaner)-no beads
Genotype: Dd Bb H
Dark hair, brown eyes, normal blood
Each female bag will have:
1 Long white chromosome -- ivory
bead (blond hair)
1 Long white chromosome -- ivory
bead (blond hair)
1 shorter white chromosome -- blue
bead (blue eye recessive)
1 shorter white chromosome -- brown
bead (brown eye dominant)
Genotype: dd Bb Hh
Blond hair, brown eyes, carrier for
hemophilia
1 pink chromosome -- purple bead
(normal)
1 pink chromosome -- clear bead
(represents a carrier for hemophilia)
Sample Answers to Sections
How to Use the Model (answers)
1. What do the pipe cleaners represent? _______chromosomes___________________
2. What do the beads represent? __alleles or genes______
3. Humans have ____23_____ pairs of chromosomes.
4. If you have two pink pipecleaners, you are playing the role of ____female__________
5. The blue pipecleaner represents the ___Y__ chromosome.
Figure out the parents traits
What color eyes does the mom have __brown_ What is her
genotype? Bb
What color eyes does the dad have? __brown_ What is his
genotype? __Bb
What color hair does mom have ? blonde What is her
genotype? dd
What color hair does dad have? dark What is his
genotype? _Dd_
Hemophilia (sex chromosomes, colored pipe cleaners)
The purple bead represents the dominant gene -- normal
The clear bead represents the recessive gene -- hemophiliac
In girls: HH = normal | Hh = normal (carrier) | hh = hemophiliac
In boys: H = normal | h = hemophiliac
What is mom's genotype? __Hh_____Is she a carrier? ____yes____
What is dad's genotype? __h__ Why doesn't dad get two alleles for this trait?_Y chromosome doesn't have allele
Determine the Traits of Your First Child and Data Table
Each cross will be different. The first cross is just to illustrate how to do the crosses. Once students understand how to do
that, the data table is easy to fill out and will go fast. You should circulate in class to help students figure out this part.
Male Genotype: Dd Bb H
Dark hair, brown eyes, normal blood
Female Genotype: dd Bb Hh
Blond hair, brown eyes, carrier for hemophilia
Using punnet squares for each cross above, it should be noted that you will never see a female child with hemophilia. If
this is seen, chances are, students got their bags mixed up during the crosses. This is the most common error, students will
not put the proper chromosomes back to the correct parent, thus making the data inaccurate. The percentages you see (at
compilation of data) should be close to:
50% dark hair, 50% blond hair
75% brown eyes, 25% blue eyes
0% hemophiliac girls
50% hemophiliac boys
Watch this video of how you would sort and then choose from each set of chromosomes. You may want to demonstrate
this to the class beforehand.
Analysis
---On a separate page, answer the following. Write answers in complete sentence and restate the question in the answer.
1. Create a punnet square for each of the crosses, using your parents. (You'll have a square for hair color, eye color, and
hemophilia)
Eye color
Bb x Bb, offspring will be 3/4 brown eyes, and 1/4 blue eyes
Hair color
Dd x dd, ofspring will be 1/2 dark hair, 1/2 blonde hair
Hemophilia
Hh x H
Female offspring will be 1/2 normal, 1/2 carriers
Male offspring will be 1/2 normal, 1/2 hemophiliacs
2. Explain why women are carrier's for the disease hemophilia. Why do their sons, but not their daughters get the disease?
Females can be carriers and will donate one of the alleles for blood proteins to their sons. Males will either receive the
normal allele or the abnormal (hemophilia). Females will also receive one of these alleles but will receive another X
chromosome from their father which will be normal (assuming dad does not have hemophilia).
3. Describe the difference between how normal traits are inherited and how sex linked traits are inherited. Sex linked traits
are inherited on the X chromosomes. Males will only receive one allele (which could be abnormal) but females will
receive two alleles and have an opportunity to inherit a normal allele from their fathers.
4. The data table where all the data is combined, shows how many ACTUAL offspring would have each of the traits. The
punnet squares (from #1) show the PREDICTED ratios. Compare the actual to predicted ratios for all three traits. The
results will be similar but probably not exact.
5. Notice on the data table that no female has the disease hemophilia. Explain why. Females inherit a normal allele from
their fathers. USE THE INFORMATION IN THE READING ON SEX-LINKED TRAITS
6. If you knew you were a carrier for hemophilia (or your wife was), would you choose to have children. Explain your
reasons. Answers vary