Pedigree Analysis
Exercise # 1
The following questions pertain to the inheritance of the earlobe trait in
humans that is thought to be controlled by a single gene. There are two
general earlobe shapes, free lobes and attached lobes. The allele
responsible for free lobes, E, is dominant to the allele for attached lobes, e.
1.
2.
3.
4.
5.
6.
Which person is the son – in – law?
To whom is the son – in – law marred?
What is the gender of their child?
What must be the genotype of person II – 1?
What is the genotype of the maternal grandmother of III – 1?
If the paternal grandmother of II – 1 had the EE genotype, what is the
genotype of the paternal grandfather, if he had free ear lobes?
7.
Can an Ee parent and an ee parent have the results shown in generation
II?
8. Predict the genotype of person II – 3.
9. Predict the genotype of person II – 4.
10. Could child II – 3 be EE? Explain your answer.
11. At some time in the future, II – 1 and II – 2 have ten more children and
all have free earlobes. What is the most likely genotype of the father?
12. How many generations are shown?
13. How many persons have free ear lobes? ___________
14. Attached ear lobes? ______________
Construct a pedigree from the information provided in the data table. Place
the man’s family on the left side of the chart, and the woman’s pedigree on
the right side
Man’s Family
Man = 24 years old; has free
earlobes
Relation
Age Phenotype
Sister
26
Attached
Mother
47
Free
Father
48
Free
Paternal
70
Free
grandmother
Paternal
77
attached
grandfather
Woman’s Family
Woman = 25 years old; has
free earlobes
Relation Age Phenotype
Brother
23
Free
Brother
16
Attached
Mother
45
Free