You are studying a population of 100 people and discover that 26 of these people are ss for a genetic condition. Use the Hardy-Weinberg equation to figure out the frequencies of the S and s alleles. What are the frequencies of the SS, Ss, and ss genotypes?
And please show your steps as to how you got your answer
And please show your steps as to how you got your answer
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p^2+2pq+q^2
ss genotype:
26/100 = 0.26 >>>This is the frequency of ss genotype because q^2 just means frequency of recessive genotype, so you already know those who are recessive....then just divide by population number (100) =]
Oh, and for frequency of s ( q) allele, just square root 0.26
One you do that you can find frequency of S (P) allele by doing 1-whateveryougotforsquarerooting0.26 =]
For the SS genotype:
This is p^2 , because P^2 stands for the dominant homozygous genotype. P+Q always = 1
We already know that q^2 = 0.26
To find out q we have to square root.
Square root of 0.26 = 0.5099019514 (we now have q)
1- 0.5099019514 = 0.4900980486 (this is p!)
So, p^2 to find out dominant genotype....
0.4900980486^2 = 0.2401960972 (this is your SS genotype, viola!)
Now, 2pq of equation is for heterozygous condition Ss
We know what p and q is from previous calculations, so...
2 x 0.4900980486 x 0.5099019514 = 0.4998039027 (This is your Ss genotype frequency)
Now, I hope the stages are clear and that I haven't made any typo's! I think if you google hardy-weinberg problems it will come up with a nice site so that you can practise these types of questions. It will help. =]
EDIT: Forgot to give you frequency of alleles. I've told you how to work it out in the first section without the answer.
ss genotype:
26/100 = 0.26 >>>This is the frequency of ss genotype because q^2 just means frequency of recessive genotype, so you already know those who are recessive....then just divide by population number (100) =]
Oh, and for frequency of s ( q) allele, just square root 0.26
One you do that you can find frequency of S (P) allele by doing 1-whateveryougotforsquarerooting0.26 =]
For the SS genotype:
This is p^2 , because P^2 stands for the dominant homozygous genotype. P+Q always = 1
We already know that q^2 = 0.26
To find out q we have to square root.
Square root of 0.26 = 0.5099019514 (we now have q)
1- 0.5099019514 = 0.4900980486 (this is p!)
So, p^2 to find out dominant genotype....
0.4900980486^2 = 0.2401960972 (this is your SS genotype, viola!)
Now, 2pq of equation is for heterozygous condition Ss
We know what p and q is from previous calculations, so...
2 x 0.4900980486 x 0.5099019514 = 0.4998039027 (This is your Ss genotype frequency)
Now, I hope the stages are clear and that I haven't made any typo's! I think if you google hardy-weinberg problems it will come up with a nice site so that you can practise these types of questions. It will help. =]
EDIT: Forgot to give you frequency of alleles. I've told you how to work it out in the first section without the answer.