Name: __________________________________________________
Period: _________ Date: _______________
Pedigree Practice #2 Worksheet
PROBLEM # 1: The pedigree below shows the recessive trait for nearsightedness in Jane’s family. Jane, her parents,
and her brother all have normal vision. Use N for the dominant allele and n for the recessive allele.
1. How many generations are represented in this pedigree? _________
2. How many children did the first couple (1 & 2) have? _____________
1
2
3. How many marriages are shown on this pedigree? _____________
4. What is the sex and genotype of individual # 2?
3
4
5
6
____________________________________________________
5. What are Jane’s possible genotypes? _________________________________
6.
5 = ___________
7.
7
What are the genotypes of individuals 5 & 6 with individual # 5 given first?
8
Jane
6 = _____________
What is the probability that individuals # 5 & 6 will have a child that is nearsighted?
____________________________________________________
PROBLEM # 2: Phenylketonuria (PKU) is an inborn error of metabolism of the amino acid phenylalanine. The following
pedigree shows a family affected by PKU (shaded in shapes). Use P for the dominant allele and p for the recessive
allele.
1. How is PKU inherited? Explain. _____________________________
_______________________________________________________
1
2
4
5
6
9
10
11
2. Which individuals in this pedigree have PKU?
______________________________________________________
3
3. What are the genotypes of individuals # 1 & 2?
#1 = _____________
#2 = _____________
7
4. What are the genotypes of individuals # 3 & 4?
#3 = _____________
8
#4 = _____________
PROBLEM # 3: Earlobes in humans are either attached (shaded in shapes) or detached. Answer the following questions
based on the pedigree below. Use F for the dominant allele and f for the recessive allele.
1. Which trait is dominant, attached or detached earlobes?
_____________________________________________
1
2
3
4
9
10
2. Which individuals in this pedigree have attached earlobes?
_____________________________________________
5
6
7
8
3. What are the genotypes of individuals # 1 & 2?
#1 = _____________
#2 = _______________
11
4. What is the genotype of individual # 4? _________________
5. What are the genotypes of individuals # 8 & 9?
#8 = _____________
#9 = ______________
12
Problem # 4: The following pedigree follows the inheritance of Huntington’s disorder (shaded in shapes) in a family.
People afflicted with Huntington’s disorder do not show symptoms until they are about 35-40 years old. Use H for the
dominant allele and h for the recessive allele.
1. Is Huntington’s disorder a Dominant or recessive trait?
1
_____________________________________________
2
3
4
2. Which individuals in this pedigree have Huntington’s?
_____________________________________________
5
6
7
8
9
11
10
3. What is the genotype of individual # 1? _____________
12
13
14
15
4. As a genetics counselor, suppose that individual # 14 and his
wife seek advice about starting a family. What would you advise them regarding the probabilities in their children?
_________________________________________________________________________________________________
PROBLEM # 5: This pedigree shows the typical inheritance pattern for Duchenne’s muscular dystrophy. Muscular
dystrophy results in muscle weakness, progressive deterioration of muscle tissue, and loss of coordination. People with
Duchenne’s muscular dystrophy rarely live past the age of 20. Use XD for the dominant allele, Xd for the recessive allele
and Y for the male chromosome.
1. How is Duchenne’s muscular dystrophy inherited? ________________
1
2
_________________________________________________________
2. What are the genotypes of individuals # 1 & 2?
3
_________________________________________________________
4
5
6
7
3. What are the genotypes of individuals # 3 & 4?
_________________________________________________________
8
9
10
11
4. What are the genotypes of individuals # 10 & 11?
_________________________________________________________
12
5. Suppose you are a genetics counselor. A married couple (# 3 & 4) seek advice
from you as to whether or not they should have children. What would you advise and why?
13
14
15
_____________________________________________________________________________________________
_____________________________________________________________________________________________
PROBLEM # 6: This pedigree shows the typical inheritance of hemophilia, a sex-linked recessive disorder. Because
their blood does not clot properly, people afflicted with hemophilia live to about 50 years old. Use XH for the dominant
allele, Xh for the recessive allele, and Y for the male chromosome.
1. How is hemophilia inherited? ____________________________________
1
____________________________________________________________
2
2. What are the genotypes of individuals # 2, 4, and 7?
#2 = __________
#4 = __________
#7 = ___________
4
3
5
6
7
3. What are the genotypes of individuals # 3, 6, and 8?
#3 = __________
#6 = __________
#8 = ___________
4. What is the probability that individual # 5 and an unaffected
8
9
10
11
12
male would have a son with hemophilia? _____________ What about have a daughter who is a carrier? _________
13