biology help asap 1. Phenylketonuria is a severe form of mental retardation caus

Question

biology help asap

1. Phenylketonuria is a severe form of mental retardation caused by a recessive allele. The condition affects about 1 in 12,000 newborn babies. In a population of 150,000 people, how many are expected to be carrier (heterozygous) for this disease? Assume Hardy-Weinberg Equilibrium (HWE). Show your work. 2. In wild petunias, the allele for red flower color (R) is dominant over the allele for white flower color (r). We sample a population and find 750 plants have white flowers and 270 have red flowers. If the population is in HWE, what are the allele frequencies of R and r in this population? How many of the 270 plants that have red flowers are homozygous and how many are heterozygous at the flower color locus? Show your work and round allele frequencies to two decimal places

Explanation / Answer

1.
PKU is an autosomal recessive disorder.
WT allele = P = Dominant
Mutant allele = p = recessive

Frequency of PKU = 1/12000 = 0.0000833
Total population size = 150000
Affected people = 12.5
q2 = 0.0000833
q = 0.00912

p = 1- 00912 = 0.990

Frequency of carriers = 2pq = 2 X 0.00912 X 0.990 = 0.0180
Number of carriers = 0.01805 X 150000 = 2708.64

2.
Dominant = R = red
Recessive = r = white

Sample size = 750 + 270 = 1020
Number of white flowered plants = 750
Frequency of white flowered plants = 750/1020 = 0.735
q2 = 0.735
Frequency of r allele; q = 0.857
Frequency of R allele; p = 1 - 0.857 = 0.1426

Frequency of heterozygotes = 2pq = 2 X 0.857 X 0.1426 = 0.244
Number of heterozygotes; Rr = 0.244 X 1020 = 248.88
Number of homozygotes; RR = 270 - 248.88 = 21.12

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