Genetics Lab Answer Sheet – This is what you should email me. To get the full extra credit, email me this
document with your answers before class on Thursday.
Use parentheses to
1. Inheritance of Albinism Meiosis->Eggs or Sperm
represent a cell.
a. Normal Haploid Cell: (A a)
Use capital letters to
b. Duplicated Chromosomes: ( fill in the alleles )
represent dominant alleles.
c. Diploid Daughter Cells:
Use small letters to
d. Haploid Daughter Cells:
represent
recessive alleles.
2.
a. What fraction of the mother’s eggs has an a allele? _______
b. What fraction of the father’s sperm has an a allele? _______
c. What fraction of this couple’s children would you expect to be aa? _______
d. Explain your reasoning
3. Do the Aa parents have normal skin and hair color or albinism? _______
4. What fraction of this couple’s children would you expect to have normal skin and hair color?
_______
5. Give an example of two individuals who have different genotypes for the albinism gene, but the
same phenotype. Explain how two individuals with different genotypes can have the same
phenotype.
6. For each of the parents, indicate the genotypes (AA, Aa, and/or aa) that could produce this
phenotype. Then, draw the Punnent squares (outcomes matrices) for these genotypes. Highlight
the albino offspring in these Punnett squares.
a. Mothers’ Phenotype: Albino; Mothers’ Genotype(s): (aa)
b. Fathers’ Phenotype: Albino; Fathers’ Genotypes(s): (aa)
Mom
Pop
I’ve completed
the first one
for you.
Pop
a
a
a
aa
aa
Mom
a
aa
aa
Pop
Mom
Mom
Pop
Depending on the
potential
genotypes of the
parents, you will
need to use 1, 2,
or all four of the
provided
matrices.
c. Mothers’ Phenotype: Albino; Mothers’ Genotype(s):
d. Fathers’ Phenotype: Normal; Fathers’ Genotypes(s):
Mom
Pop
Mom
Pop
Mom
Pop
Mom
Pop
e. Mothers’ Phenotype: Normal; Mothers’ Genotype(s):
f. Fathers’ Phenotype: Normal; Fathers’ Genotypes(s):
Mom
Pop
Mom
Pop
Mom
Pop
Mom
Pop
g. Which couple would be the most likely to have albino children? Indicate their genotypes
below.
i. Mom’s genotype:
ii. Pop’s genotype:
h. Which couple would be the least likely to have albino children?
i. Mom’s genotype:
ii. Pops’s genotype
7. Explain why two albino parents will not have any children with normal skin and hair color, but
two parents with normal skin and hair color could have an albino child.
8. Coin toss genetics: Don’t find someone to “mate” with. Just flip your coin twice. Let the first flip
be the “egg” and the second be the “sperm.” Each family has four children and you’re tosses will
determine the composition of the family. Please record the number of children that have the
following genotypes for each family and the totals. William will reveal the outcomes of the
classes coin tosses at the next lab meeting.
First family of 4
Second family of 4
Third family of 4
Fourth family of 4
Totals
Predictions
# AA Children
# Aa Children
# aa Children
4
8
4
9. Normal red blood cells can barely squeeze through the capillaries. What problems might be
caused by sickle-shaped blood cells?
10. Most children with sickle cell anemia have parents who do not have sickle cell anemia. Explain
how a person can inherit sickle cell alleles from parents who do not have sickle cell anemia. Is
the sickle cell allele dominant (S) or recessive (s)? Explain your reasoning. Include a Punnett
Square in your answer.
Mom
Pop
11. Rasheda and Craig do not have sickle cell anemia, but their first child has sickle cell anemia.
What is the probability that their second child will have sickle cell anemia? Explain your
reasoning?
12. Explain how the hemoglobin gene illustrates the following generalization: A single gene often
has multiple phenotypic effects.
13. How do the examples involving sickle cell and normal alleles for the hemoglobin gene explain
the general principle that neither allele is completely dominant or completely recessive? Note
that this incomplete dominance is consistent with Blending inheritance models.
This answer sheet is derived heavily from the Genetics handout created by Drs. Poethig, Waldron, and
Doherty in 2013. For the original or more materials created by these individuals, please check
http://serendip.brynmawr.edu/sci_edu/waldron/#genetics .