Download Hardy-Weinberg Problems (BSC 1011C)

Hardy-Weinberg Problems (BSC 1011C)
1) According to the Hardy-Weinberg equation, what conditions must be met in order
for the allelic frequencies to remain constant throughout successive generations?
2) One in 1700 Caucasian newborns have cystic fibrous (C is the dominant allele, c
the recessive).
a. When counting phenotypes in a population, why is the cc genotype the
most significant?
b. What percent of the above population have cystic fibrous?
c. How many members of the population are carriers for cystic fibrous?
d. How many members of the population are homozygous normal?
3) If 9% of an African population is born with sickle-cell anemia (genotype: ss),
what percentage of this population will be resistant to malaria. Recall carriers of
sickle-cell anemia benefit from heterozygote advantage and are resistant to
malaria.
4) You and 19 of your friends (20 people total) build a raft and sail to a deserted
island where you remain for the rest of your lives. No one else ever comes to this
island as it is totally isolated. Two of your friends carry (they are heterozygous)
for a particular genetic disease.
a. Assuming all the conditions of the Hardy-Weinberg equilibrium are
maintained, what will be the percentage of individuals on the island who
will have the disease?
b. Assuming the frequency of this disease is 0.059% on the mainland, how
many more times greater is the prevalence of this disease on the island vs.
the mainland?
5) A plant population consists of two flower morphs, white and red, controlled by a
single locus and two alleles. The white morph represents the recessive
homozygote. The red morph consists of some combination of heterozygotes and
dominant homozygotes. Assume that 50% of the population has red flowers.
a. What are the frequencies of all three genotypes assuming Hardy-Weinberg
equilibrium?
6) The B allele is dominant to the b allele. The phenotype associated with the former
is brown eyes, while blue eyes is the phenotype associated with the latter. The
brown eye allele is present in the population at a frequency of 0.2.
a. Given Hardy-Weinberg equilibrium and no differences in allele
frequencies between genders, what is the probability that a blue-eyed
woman will marry a brown-eyed man?
7) A population consists of 200 individuals with an aa genotype (homozygous
recessive) and is in Hardy-Weinberg equilibrium.
a. What is the frequency of the a allele if the population consists of a total of
1,000 individuals?
b. What is the frequency of the a allele if the population consists of a total of
10,000 individuals?
8) In a hypothetical population of 2500 people, 2275 people have brown eyes and
225 people have blue eyes (the homozygous-recessive phenotype).
a. If there are 4000 children produced by this generation, how many of the
children would be expected to be heterozygous for eye color assuming
Hardy-Weinberg equilibrium?
9) Data from 400 Basques from Spain report 230 were Rh+ and 170 were Rh-.
a. Calculate the allele frequencies of d (the recessive allele).
b. Calculate the allele frequencies of D (the dominant allele).
c. How many of the Rh+ individuals would be expected to be heterozygous
(Dd)?
10) The dry type of ear cerumen ("wax") is due to homozygosity for a simple
Mendelian recessive. Among American Indians the frequency of dry-cerumen
individual is 66 percent.
a. What is the frequency of the recessive allele?
11) The gene for albinism is known to be a recessive allele. In Michigan, 9 people in
a sample of 10,000 were found to have albino phenotypes. The other 9,991 had
normal skin pigmentation.
a. Assuming Hardy-Weinberg equilibrium, what is the allele frequency for
the dominant pigmentation allele in this population?
b. How many out of the 10,000 people in the sample above were expected to
be heterozygous for pigmentation?
c. A similar survey was carried out in Wisconsin, but only 2,500 people were
surveyed. If allele frequencies are the same in Wisconsin as they are in
Michigan, how may people would you expect to have the albino
phenotype in this sample?
12) Using the class results from the PTC paper test, calculate the following.
a. What is the frequency of the recessive allele?
b. What is the frequency of the dominant allele?
c. How many heterozygotes are there?
d. How many homozygous dominants are there?