Suppose the human trait for freckles is controlled by a simple dominant and rece

Question

Suppose the human trait for freckles is controlled by a simple dominant and recessive relationship at one locus. Freckles, F, is the dominant allele, and a lack of freckles, f, is the recessive allele. In a college genetics class, the professor takes a tally of the number of students who have freckles and those with a lack of freckles. In this class of 123 students, 98 have freckles. Calculate the frequency of the dominant allele, F, and the heterozygous genotype, Ff. Express the frequencies in decimal form rounded to the nearest thousandth. Assume the class is in Hardy-Weinberg equilibrium for this trait.

Explanation / Answer

Answer:

Freckles, F, is the dominant allele,

and a lack of freckles, f,

q^2= 98/123 =0.79

q= square root of 0.79

q=0.89

p+q=1

p=1-q

p=1-0.89 =0.11

the frequency of the dominant allele, F= 0.11

Frequency of heterozygous genotype is (2pq) = 2 x 0.89 x 0.11 = 0.198 = 20%

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