Question

1. in a population of fruit flies, 250 are homozygous dominant for red eye. the remaining 250 flies have homozygous dominant for red eyes and 500 are heterozygous for red eye. the remaining 250 flies have white eyes. given this information, calculate the following:

a. the frequency of the dominant allele:
b. the frequency of the recessive allele:
c. the frequency of the homozygous dominant genotype:
d. the frequency of the heterozygous genotype:
e. the frequency of the homozygous recessive genotype:

1. brown fur is dominant to white fur in mice. in a population of mice, 74% have brown fur and 26% have white fur. based on these facts, calculate the following:

a. the frequency of the dominant allele:
b. the frequency of the recessive allele:
c. the percentage of mice that are homozygous dominant:
d. the percentage of mice that are heterozygous:
e. the percentage of mice that are homozygous recessive:

Explanation:

Step1: Calculate total number of flies in fruit - fly population

The total number of fruit - flies is $250 + 500+250=1000$.

Step2: Calculate allele frequencies in fruit - fly population

Let $p$ be the frequency of the dominant allele and $q$ be the frequency of the recessive allele.
The number of dominant alleles: $2\times250 + 500=1000$.
The number of recessive alleles: $2\times250=500$.
The total number of alleles: $2\times1000 = 2000$.
$p=\frac{1000}{2000}=0.5$ and $q=\frac{500}{2000}=0.5$.

Step3: Calculate genotype frequencies in fruit - fly population

The frequency of the homozygous dominant genotype ($AA$) is $p^{2}=(0.5)^{2}=0.25$.
The frequency of the heterozygous genotype ($Aa$) is $2pq = 2\times0.5\times0.5=0.5$.
The frequency of the homozygous recessive genotype ($aa$) is $q^{2}=(0.5)^{2}=0.25$.

Step4: Calculate allele and genotype frequencies in mouse population

Let $p$ be the frequency of the dominant allele and $q$ be the frequency of the recessive allele for mouse fur color.
Since the frequency of white - fur mice (homozygous recessive, $q^{2}$) is $0.26$, then $q=\sqrt{0.26}\approx0.51$.
$p = 1 - q=1 - 0.51 = 0.49$.
The percentage of homozygous dominant mice is $p^{2}=(0.49)^{2}\approx0.24$.
The percentage of heterozygous mice is $2pq=2\times0.49\times0.51\approx0.50$.
The percentage of homozygous recessive mice is $q^{2}=0.26$.

Answer:

Fruit - fly population:
a. The frequency of the dominant allele: $0.5$
b. The frequency of the recessive allele: $0.5$
c. The frequency of the homozygous dominant genotype: $0.25$
d. The frequency of the heterozygous genotype: $0.5$
e. The frequency of the homozygous recessive genotype: $0.25$

Mouse population:
a. The frequency of the dominant allele: $0.49$
b. The frequency of the recessive allele: $0.51$
c. The percentage of mice that are homozygous dominant: $0.24$
d. The percentage of mice that are heterozygous: $0.50$
e. The percentage of mice that are homozygous recessive: $0.26$