. A population in Chile that lives in a harsh desert environment had an outbreak
ID: 50394 • Letter: #
Question
. A population in Chile that lives in a harsh desert environment had an outbreak of cholera during the summer that killed many people. This population was tested for the presence of CFTR alleles. The numbers of each genotype in the population before and after the outbreak are shown below.
+ / + + / F508 F508 / F508 Total
Spring 1575 540 85 2200
Fall 660 540 0 1200
What is the fitness of each genotype?
What is the allele frequency in the population in the fall after the cholera outbreak? P c.Assuming no further occur, what will be the allele frequencies in the next generation?
d. What will be the genotype frequencies in the next generation
e. Provide a biochemical, cellular, or molecular hypothesis as to why the three different genotypes should have different fitness.
Explanation / Answer
** first calculate the survival rate of each genotype. +/+ = (660/1575) *100 = 42%
+ / F508 = 100% F508 / F508 = 0
fitness of +/+ = survival rate of genotype/maximum genotype = 42/100=0.42
fitness of + / F508 = 100/100 = 1
fitness of F508 / F508 = 0
allelic frequency of + allele will be = f(+/+) + 1/2
d. genotype frequency after outbreak of (+/+) = 660/1200 = 0.55 = 55%
genotype frequency of (+ / F508) after outbreak = 540/1200 = 0.45 =45%
genotype frequency of (F508 / F508) after outbreak = 0
**allele frequency in the population in the fall after cholera outbreak= Applying Hardy-weinberg's law, allele frequency will remain same in all generations.
allelic frequency of + = 540 + (2*660) / 2*660 +2*540 + 2*0
= 1860/1320 +1080 = 1860/2400=0.77 (in other words, 77% population is having + allele)
and the rest 1-0.77 = 0.23 ; 23% population is having the F508 allele
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