In 1927, the ophthalmologist George Waaler tested9049 schoolboys in Oslo, Norway, for red-green colorblindness and found 8324 of them to be normal and725 to be color blind. He also tested 9072 schoolgirlsand found 9032 that had normal color vision while40 were color blind.a. Assuming that the same sex-linked recessive allelec causes all forms of red-green color blindness,calculate the allele frequencies of c and C (the allelefor normal vision) from the data for the schoolboys.(Hint: Refer to your answer to Problem 12a.)b. Does Waaler’s sample demonstrate Hardy-Weinbergequilibrium for alleles of this gene? Explain youranswer by describing observations that are eitherconsistent or inconsistent with this hypothesis.On closer analysis of these schoolchildren, Waalerfound that there was actually more than one c allelecausing color blindness in his sample: one kind forthe prot type (cp) and one for the deuter type (cd).(Protanopia and deuteranopia are slightly differentforms of red-green color blindness.) Importantly,some of the apparently normal females in Waaler’s studies were probably of genotype cp/cd. Through further analysis of the 40 color-blind females, he foundthat 3 were prot (cp/cp), and 37 were deuter (cd/cd).c. Based on this new information, what are thefrequencies of the cp, cd, and C alleles in the population examined by Waaler? Calculate these valuesas if the frequencies obey the Hardy-Weinbergequilibrium. (Note: Again, refer to your answer toProblem 12a.)d. Calculate the frequencies of all genotypes expectedamong men and women if the population is atequilibrium.e. Do these results make it more likely or less likelythat the population in Oslo is indeed at equilibriumfor red-green color blindness? Explain yourreasoning.
In 1927, the ophthalmologist George Waaler tested
9049 schoolboys in Oslo, Norway, for red-green color
blindness and found 8324 of them to be normal and
725 to be color blind. He also tested 9072 schoolgirls
and found 9032 that had normal color vision while
40 were color blind.
a. Assuming that the same sex-linked recessive allele
c causes all forms of red-green color blindness,
calculate the allele frequencies of c and C (the allele
for normal vision) from the data for the schoolboys.
(Hint: Refer to your answer to Problem 12a.)
b. Does Waaler’s sample demonstrate Hardy-Weinberg
equilibrium for alleles of this gene? Explain your
answer by describing observations that are either
consistent or inconsistent with this hypothesis.
On closer analysis of these schoolchildren, Waaler
found that there was actually more than one c allele
causing color blindness in his sample: one kind for
the prot type (cp
) and one for the deuter type (cd
).
(Protanopia and deuteranopia are slightly different
forms of red-green color blindness.) Importantly,
some of the apparently normal females in Waaler’s studies were probably of genotype cp
/cd
. Through further analysis of the 40 color-blind females, he found
that 3 were prot (cp
/cp
), and 37 were deuter (cd
/cd
).
c. Based on this new information, what are the
frequencies of the cp
, cd
, and C alleles in the population examined by Waaler? Calculate these values
as if the frequencies obey the Hardy-Weinberg
equilibrium. (Note: Again, refer to your answer to
Problem 12a.)
d. Calculate the frequencies of all genotypes expected
among men and women if the population is at
equilibrium.
e. Do these results make it more likely or less likely
that the population in Oslo is indeed at equilibrium
for red-green color blindness? Explain your
reasoning.
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