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attac 2. (2.5 pts) Based on an example of fitness in sickle cell genotypes, use

ID: 197655 • Letter: A

Question

attac 2. (2.5 pts) Based on an example of fitness in sickle cell genotypes, use the Hardy/We natural selection has led to evolution in the population below. nber g formula to determine if Step 2 Step 1 Observed o aileles Observed Genotypes # of 1 genotype 45 40 15 100 people FrequenciesA AS sS Total 1.00 Step 3 allele frequencies Step 4 Plug the allele frequencies into the Hardy/Weinberg formula (p2+2pq+-1) to get the expected genotype frequencies for AA, AS, and SS Step 5 Compare the observed genotype frequencies from step #1 to the expected genotype frequencies from ste # 4, Are they all the same? genotype frequencies that 2 Do you observe any occur more or less than expected, as predicted by Hardy/Weinberg? Step 1 Step 5 types obs AS

Explanation / Answer

Allele frequencies estimation:

Genotype

Freequency

Allele A

Allele S

Total

AA

45

90

0

90

AS

40

40

40

80

SS

15

0

30

30

Total

100

130

70

200

Allele A

= 130 / 200

= 0.65

Allele S

= 70 / 200

= 0.35

Expected Genotype Frequencies

AA

= 0.65* 0.65 = 0.423

*100 = 42

AS

= 2 * 0.65 *0.35 = 0.455

*100 = 46

SS

= 0.35* 0.35 = 0.123

*100 = 12

Chisquare test:

Null hypothesis: The observed values are not deviating from the expected values.

Test static:

Category

AA

AS

SS

Observed values

45

40

15

Exprected Values

42

46

12

Deviation

3

-5

3

D^2

7.5625

30.25

7.5625

D^2/E

0.18

0.66

0.62

1.46

X^2

1.46

Degrees of freedom

1

Inference: The calculate chisquare value i.e. 1.46 is less than the table value i.e. 3.84 at 3 DF and 0.05 probability, hence the null hypothesis is accepted. Which means the population is in HW equilibrium.

Genotype

Freequency

Allele A

Allele S

Total

AA

45

90

0

90

AS

40

40

40

80

SS

15

0

30

30

Total

100

130

70

200