Question

beetles! (Show all your calculations below)_250/1000 :.25 =q? (Ooo total 92.25 p = PP : 250 q=.5 pt.5-1 Pp: 500 a=green D: purple Frequency of P? S2 Frequency of p?_.5 PP: 250 P².5 (f) Has the population evolved?_yes Explain. alle frequencies Chanenfum Oyidik valves 3. Scientists have known for some time that humans carry a genetic mutation (known as CCR5-delta 32) that prevents the HIV virus from entering the cells of the immune system but have been unable to account for the high levels of the gene in Scandinavia and Russia populations. They have also been puzzled by the fact that HIV emerged only recently and could not have played a role in raising the frequency of the mutation to the high levels found in some Europeans today. The fact that the CCRS-delta 32 mutation is restricted to Europe suggests that the plagues of the Middle Ages played a big part in raising the frequency of the mutation. The plagues of Europe (1347-1660) were in fact a continuing series of epidemics of a lethal, viral, hemorrhagic fever that used the CCRS as an entry port into the immune system. This disease provided the selection pressure that increased the frequency of the mutation from 1 in 20,000 to values today of 1 in 10. Hemorrhagic plague did not disappear after the Great Plague of London in 1665-66 but continued in Sweden, Copenhagen, Russia, Poland and Hungary until 1800. This continuance of hemorrhagie plague provided selection pressure on the CCRS-delta 32 mutation and explains why it occurs today at its highest frequency in Scandinavia and Russia populations.

Answer 1

Hardy - Weinberg equilibrium can be used to identify the frequency of the population that are homozygous or heterozygous for the CCR5-delta 32 mutation.

Consider the target genes with two alleles, p and q

p - frequency of CCR5-delta 32 mutant allele

q - normal wild type allele susceptible to HIV

By Hardy - Weinberg equilibrium,
p+q=1
and
p2 + 2 + 2pq = 1

Here, p =10% = 0.1 and therefore q = 90% = 0;9

a) Percent of population having 2 copies of the delta 32 allele and are immune to HIV infection is = $0.1^{2}$ =
0.01 = 1
%

Therefore, 1% of the population carries 2 copies of the delta 32 mutated allele and are immune to the HIV infection

b) Percent of population that are heterozygous (i.e. carrying one mutant delta 32 allele and a normal allele) is given by

2pq = 2*0.1*0.9 = 0.18 = 18%

18% of population are heterozygous and are less susceptiible to HIV infection

c) During middle ages, when the Swedish population carried 1% of the delta 32 allele the percentage of population that carries two copies of the delta 32 allele is given by the above Hardy - Weinberg equilibrium with p and q value varies to 0.01 and 0.99

Then, %

p = 0.012 = 0.0001 = 0.01

0.01% of population are homozygous to the delta 32 mutant allele and are immune to HIV during the middle ages

d) The frequency of the HIV immune individuals in today's population than in the Middle Age population is given by

1% / 0.01% = 100%   that gives the frequency of 1

That, their is an 100% more HIV immune individual than that in Middle ages

e) If there was not any drug effective in killing HIV, then the frequency of the delta 32 allele will raise up in the upcoming population due to the selective pressure that is posed by the virus upon the Human population.