Download Case Study: Sickle Cell Anemia

Practicing Punnett Squares
Directions: Answer the following questions on a piece of binder paper. Be sure to show punnett
squares to prove your answers.
Case Study: Sickle Cell Anemia
Sickle-cell anemia is known to be a hereditary disease. It has a pattern of inheritance that closely
follows the model for recessive traits described by early geneticist Gregor Mendel. For a recessive
trait to appear, a person must have inherited to copies of the recessive gene.
1. John and his wife Anna are heterozygous for Sickle-cell. Create a Punnett Square to
analyze the odds of any offspring inheriting sickle-cell anemia.
2. If their child who has both normal hemoglobin genes marries a person who has sickle-cell
anemia, what is the probability of any of their offspring inheriting sickle-cell anemia (use a
punnett square)?
3. If a person has anemia, his or her blood cells are oxygen deprived. Describe to this couple
how a person with sickle-cell anemia might feel.
4. Why would simple blood transfusions not be able to cure this disease?
Punnett Squares: Why Do I (or don’t I) Have Freckles and Curly Hair?
Solve the genetics problems below by using punnett squares. Write your answers on a separate
piece of paper. Staple your answer sheet to this worksheet.
The gene for freckles has two alleles.
F =freckles (dominant allele)
f=no freckles (recessive allele)
1. a. Dan is homozygous for freckles. His wife, Deborah, does not have any freckle. Create a
punnett square to predict the results of their children.
b. What percentage of their children will have freckles?
c. What percentage of their children will not have freckles?
2. a. Sara and Justin both have freckles and both are heterozygous for this trait. Create a
punnett square to predict the results of their children.
b. What are the chances they will have a child with freckles?
c. What is the chance they will have a child with the FF genetic makeup?
3. a. Do you have freckles?
b. What are the possible allele combinations you could have?
The gene for hair style has two alleles.
C= curly hair (dominant allele)
c= straight hair (recessive allele)
4. Gloria has straight hair and her husband, Andre, also has straight hair. What percentage of
their children will have curly hair? Create a punnett square to show the results.
5. Maria has straight hair. Her mother, Irma, has curly hair and her father, Pedro, also has curly
hair. How did Maria get straight hair? Create a punnett square to show the results.
6. Camille has curly hair. Her mother, Giselle, also has curly hair, but her dad, Wolfgang, has
straight hair. What is Camille’s allele combination? Explain.
7. a. Do you have curly hair?
b. How could you find out your specific allele combination with respect to your hair style?