Download Bowman Pedigree Project

Name: _______________________________________________________________ Class: ____________
Biology 9 - Genetics
Case Study: Albinism in the Bowman Family
Overview:
The Bowman family makes an excellent case study for genetic inheritance for two reasons. First, they have a really big
family. This allows us to see the effects of probability on each offspring more easily. Secondly, some members of the
Bowman family have an interesting genetic trait – albinism. Albinism is a genetic condition characterized by a lack of
pigment which results in extremely light skin, hair, and eyes.
Your task in this case study is to analyze some information about the Bowman family in order to determine the genetic
inheritance pattern of albinism. Is it dominant, recessive, or codominant? Or is it controlled by more than one genes
(polygenic)? You are also responsible for determining the genotype of key members of the Bowman family, and then for
doing some further genetic analysis of the traits that they show.
This case study is structured like a formal lab report in that you will gather background information, make a hypothesis,
work with data, do some analysis, and form some conclusions. However, you will not actually type up the lab report – all
the work will be completed in this packet.
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Background Information – Notes: Take notes here based on Ms. Bowman’s presentation!
Background Information - Paragraph: Use the space below to write a well-connected paragraph that explains
important background information about albinism and/or the Bowman family.
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Purpose & Hypothesis:
The purpose of this case study is to ____________________________________________________________________
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Hypothesis:
 Do you predict that albinism is dominant, recessive, codominant, or polygenic? ___________________________
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Why? ______________________________________________________________________________________
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Procedure & Data
1. On the next page, draw a pedigree diagram representing the Bowman family. In a pedigree diagram:
 Circles represent females and Squares represent males
 Horizontal lines connecting two people mean that they had children together
 Vertical lines connect parents with their offspring
 Shaded shapes mean that the person has the trait you are studying
An example pedigree diagram is on the board.
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Use the table on page 5 to guide you – it has all the necessary information about the Bowman family that you’ll
need to make your pedigree.
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Your pedigree diagram should have a title and a key.
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You may want to turn the paper sideways and draw your pedigree going across the long way on the page, so that
you have enough room.
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2. Before moving on, get your pedigree approved by your instructor: ___________
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Use the information in this table to make your pedigree:
THE BOWMAN FAMILY – 3 Generations
Name
Parents
Phenotype
Mom
light brown hair, green eyes
Dad
dark brown hair, blue eyes
Possible genotype(s) for
albinism
Possible genotype(s) for
hair and eye color
Children (in order, eldest to youngest)
Billy
light brown hair, brown eyes
Mike
has albinism
Betsy (Ms.
Bowman)
has albinism
Meg
light brown hair, hazel eyes
Tricia
has albinism
JJ
dark brown hair, blue eyes
Chris
dark brown hair, brown eyes
Bobby
dark brown hair, blue eyes
Peter
light brown hair, blue eyes
Some of the spouses and grandchildren
Tricia’s family:
Brian (husband)
dark brown hair, brown eyes
Joseph (son)
dark brown hair, brown eyes
Lucy (daughter)
dark brown hair, brown eyes
Olivia (daughter)
dark brown hair, brown eyes
Chris’s family:
Isabelle (wife)
blond hair, blue eyes
Jack (son)
blond hair, blue eyes
Leo (son)
blond hair, blue eyes
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3. Now you need to study your pedigree and figure out the inheritance pattern of albinism. Is albinism a
dominant trait? A recessive trait? Or is something different (such as codominance or polygenics) going on?
You may want to get some scrap paper and try out different Punnett Squares until you find one that works.
Basic Conclusions:
What is the inheritance pattern of albinism – is it dominant, recessive, or something else? Explain in detail
your reasoning for your answer. You may want to refer to a Punnett Square, which you will draw below.
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What are the genotypes of…
Dad Bowman __________
Mom Bowman __________
Use their genotypes to draw a Punnett Square showing the possible offspring that they could have:
Now go back to the table on page 5. Fill in the possible genotypes for each member of the family. For
some, you should be able to write one definite genotype. For others, you should write as many possibilities as it
could be.
Analysis
4. Compare your conclusion for the inheritance pattern of albinism with your hypothesis. Was your
hypothesis correct? _______ If not, explain why it was wrong:
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5. What is the actual proportion (or percentage) of Bowman children (ignore the spouses and grandchildren
for this question) who have albinism, out of all of Mr. and Mrs. Bowman’s kids?
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What is the expected proportion (or percentage) of Mr. and Mrs. Bowman’s children that were likely to
have albinism, based on your Punnett Square?
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How closely do the actual numbers match your predictions? Is this expected or unexpected? Explain your
answer.
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6. Compare two sets of Bowman grandchildren – Trisha’s kids and Chris’s kids.
a. What are the chances that Trisha’s kids are carriers (this means they are heterozygous but don’t
show the trait) for albinism? Explain your answer!
b. What are the chances that Chris’s kids are carriers for albinism? (This one is a little trickier to
figure out – explain either in words or some probability math)
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7. Michael (the 2nd Bowman child) is married to Alysia. Alysia is of Chinese descent, so she has black hair
and dark brown eyes. They do not have any children yet.
a. What is Alysia’s most likely genotype for albinism? ___________
b. Assuming that you are correct, draw a Punnett Square showing how the albinism allele will be
passed down to Michael and Alysia’s future children:
c. What is the probability that Michael and Alysia will have a child with albinism? _________
d. What is the probability that they will have a child who is a “carrier” (this means heterozygous) for
albinism? _________
8. Dark brown hair (D) is dominant over light brown hair (d). Blue eyes (e) are recessive, so anyone with
another color has at least one dominant allele (E).
a) In the table on page 5, fill in the final column of genotypes for hair color and eye color for all family
members except those with albinism. (Hint: start with Peter! Then figure out the parents, and then fill
in everyone else.)
b) Make a Punnett square showing predicted ratios of genotypes and phenotypes for hair and eye color in
the Bowman children, based on their parents’ genotypes. Make sure you write the predicted ratios
for every combination of hair/eye colors after you draw your Punnett Square.
c) How closely do the actual numbers of children match these predictions?
Bonus: Read the article entitled “Albino Like Me,” which was published in the Boston Globe a couple of years
ago. Then answer the questions at the end of the article.
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