A.In a population of 25,000 fruit flies, 20,000 have the dominant trait of long

Question

A.In a population of 25,000 fruit flies, 20,000 have the dominant trait of long wings, 5,000 have the recessive trait. Using Hardy-Weinberg equations, calculate the frequency of:

1. the recessive trait:

2. the recessive gene:

3. the dominant gene:

4. the homozygous dominant individuals:

5. the heterozygous individuals:

B. In the same population of fruit flies, 10 generations later the frequency of homozygous recessive individuals was 0.01. Using the Hardy-Weinberg assumptions, explain what has happened

C. In African- Americans, sickle cell anemia can be considered as a recessive trait. If 1 out of 500 African-American have sickle cell anemia, what percent would be estimated to be carriers?

Explanation / Answer

Answer:

A).

1). Frequency of recessive trait = q^2 = 5000/25000 = 0.2

2). Frequency of recessive allele (gene) = q = SQRT of q^2 = 0.45

3).

As p+q=1

The frequency of dominant allele (gene) = p = 1-q = 1-0.45 = 0.55

4). Frequency of homozygous dominant trait = p^2 = 0.55 * 0.55 = 0.3

The number of homozygous dominant individuals = 0.3 * 25000 = 7500

5). Frequency of heterozygous dominant trait = 2pq = 2*0.55 * 0.45 = 0.5

The number of heterozygous dominant individuals = 0.5 * 25000 = 12500

B). -------

C). Frequency of sickle cell anemia = q^2 =

1/500 = 0.002

Frequency of sickle cell allele = q = 0,045

As p+q=1

Frequency of normal allele = p = 1-q = 0.955

Frequency of carriers = 2pq = 2 * 0.955 * 0.045 = 0.086

Carrier individuals = 0.086 * 500 = 43

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