Name
WHO
GET’S
THE
MONEY?
Purpose:
To solve a mystery involving genetics.
Background:
Mr. and Mrs. John Jones died in a tragic farm accident when the tractor they
were riding on rolled over in a ditch. Authorities found three million dollars
hidden in a feed bin in the chicken coop. The couple is known to have a son,
from whom they are estranged. This man is the sole heir to the Jones fortune.
Five men show up, each claiming to be the couples’ long lost son who had run
away to become a sheep-herder. You are called in as a genetics expert to decide
who is the rightful heir. This mystery will be solved in three parts.
PART ONE: Complete Dominance (Dihybrid)
Brown eyes are dominant over blue eyes, free earlobes are dominant over attached earlobes.
Mr. Jones
Heterozygous free earlobes and dominant brown eyed
Mrs. Jones
Hybrid for earlobes and heterozygous for eye color.
Carl
Attached earlobes and homozygous brown eyed
Ray
Homozygous free earlobes, blue-eyed
Dale
Hybrid for earlobes, homozygous brown-eyed
Earl
Heterozygous free earlobes and heterozygous brown-eyed
Robert
Homozygous dominant for earlobes and blue-eyed
What are the genotypes of Mr. and Mrs. Jones?
What are the possible genotypes of the offspring?
Write each person’s genotypes in the chart below:
Person
Genotype
Carl
Ray
Dale
Earl
Robert
Which men can be eliminated by these traits? Explain your reasoning for each man.
PART TWO: Codominance and Incomplete Dominance
Now that _____________________________________________ have been eliminated, lawyers order blood tests
to try to prove their claims. The lawyers have also done some research and read that hair texture is inherited.
Type A and Type B blood are codominant over Type O
Rh+ blood is dominant over Rh- blood.
Hair texture exhibits incomplete dominance. Homozygous (HH) have curly hair. Homozygous (AA) have straight
hair. Heterozygotes (HA) have wavy hair.
Mr. Jones
Homozygous type A blood, heterozygous Rh+, straight hair
Mrs. Jones
Heterozygous type B blood, homozygous Rh+, wavy hair
Carl
Heterozygous type A blood, heterozygous Rh+, wavy hair
Ray
Type AB blood, homozygous Rh+, wavy hair
Dale
Heterozygous type A blood, homozygous Rh+, wavy hair
Earl
Type O blood, Rh-, straight hair
Robert
Homozygous type A blood, heterozygous Rh+, wavy hair
What are the genotypes of Mr. and Mrs. Jones?
What are the possible genotypes of the offspring? (May be easier to write blood type with Rh separate than
hair texture).
To simplify, 3 separate punnett squares could be drawn and analyzed separately. One for blood type and
then perform one for Rh factor separate. Then another for hair texture. Or you may use the space to work
another way.
Write each person’s genotypes in the chart below:
Person
Blood Type
Rh Type
Carl
Ray
Dale
Earl
Robert
Which men can be eliminated by these traits? Explain your reasoning for each man?
Hair Texture
PART THREE: Epistasis
Now, we are just down to _____________________ and _______________________. Let’s find out which one of
them is the legitimate son.
(Note: The following is hypothetical):
In humans, D allows for 3-D vision and is dominant over d which allows for 2-D vision. Another gene
determines whether an individual can see or not. Allele e allows individuals to see, but the mutant allele E
prevents sight all together.
Mr. Jones
Heterozygous for vision type; Recessive for sight
Mrs. Jones
Heterozygous for vision type; Hybrid for sight
Carl
Unfortunately is blind (homozygous dominant) since
he is homozygous dominant for 3-D
Sees in 2-D vision
Hybrid genotype for vision, but hybrid for sight
homozygous dominant for vision and can see
Homozygous dominant for both
Ray
Dale
Earl
Robert
What are the genotypes of Mr. and Mrs. Jones?
What are the possible genotypes of the offspring?
Write each person’s genotypes in the chart below:
Person
Carl
Ray
Dale
Earl
Robert
SO, WHO GETS THE MONEY?
Genotype
You can test yourself for astigmatism:
1.
2.
Stand about 20 feet away from the chart.
You can have astigmatism in one eye but not the other. Therefore
you have to test one eye at a time. Close or hold on eye shut and
view the chart (when done, repeat with other eye):
Do you see the chart clearly (3 individual lines for each number)?
NO ASTIGMATISM
Do you see some “grouping” of lines so it looks like a thicker black line,
or all 3 lines grouped as one?
ASTIGMATISM