3. Scientists determined the genotypes of 122 Havasupai people, a group of Nativ
ID: 191749 • Letter: 3
Question
3. Scientists determined the genotypes of 122 Havasupai people, a group of Native Americans in Arizona. The two genes are located in the major histocompatibility complex (MHC), an important part of the immune system. The following data are the number of observed and number of expected people for the HLA-A and HLA-B genes. Observed Expected HLA-A Homozygotes Heterozygotes 38 84 48.43 73.57 HLA-B Homozvgotes Heterozygotes 21 101 29.56 92.44 Do the observed data significantly differ than expected? Why or why not? (NOTE: calculate each gene separately.) a. b. What might explain the relatively high frequency of heterozygotes?Explanation / Answer
A) For HLA-A
Observed
AA=38
Aa= 84
Expected
AA= 48.43 (p2 x 122)
Aa= 73.57 (2pq x 122)
From above given data,
the frequency of allele A= p = [(2 x 38)+84]/244
p= 0.6557
the frequency of allele a= q= [84/122]
q= 0.6885
Consider what the expected genotype frequencies will be, if the population is in hardy-weinberg equilibrium and compare these with the observed value.
these observed and expected values are different significantly from those expected if the population is not in equilibrium.
HLA-B
Observed
BB=21
Bb= 101
Expected
BB= 29.56 (p2 x 122)
Bb= 92.44 (2pq x 122)
From above given data,
the frequency of allele B= p= [(2 x 21)+101]/244
p= 0.5860
the frequency of allele b= q= [101/122]
q= 0.8278
Now consider , if the population is in hardy-weinberg equilibrium and compare these with the observed value and what the expected genotype frequencies would be like
these observed and expected values are different significantly from those expected if the population is not in equilibrium. These values are cosiderably different, with same number of homozygous of both HLA-A and HLA-B in observed value. Heterogygotes possess increased numbers than homozygotes in HW deviation.
B) Relative high frequency of heterozygotes found in HW deviation from part A calculation. Such as advantages or negative assortative mating, that is the attraction of opposites.
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