Tay–Sachs disease is an autosomal recessive neurological disorder...

Question

Tay–Sachs disease is an autosomal recessive neurological disorder that is fatal in infancy. Despite its invariably lethal effect, Tay–Sachs disease occurs at very high frequency in some Central and Eastern European (Ashkenazi) Jewish populations. In certain Ashkenazi populations, 1 in 750 infants has Tay–Sachs disease. Population biologists believe the high frequency is a consequence of genetic bottlenecks caused by pogroms (genocide) that have reduced the population multiple times in the past several hundred years.

In the population described, what is the frequency of the recessive allele that produces Tay–Sachs disease?

Accepted Answer

Hello, everyone and welcome to today's video. So about one in 625 infants suffer from cystic fibrosis in a small population that experience a catastrophic event on an island to determine the frequency of the recessive that produces cystic fibrosis. Now as the answer choice, A we have 0.2 B 0.4 C 0.8 D 0.12. So in order to solve this problem, we need to recall the Hardy Weinberg equation which is going to be P square equals or P square plus two P Q plus Q square is going to be equal to one. Now remember that cystic fibrosis is going to be a recessive disease. So if we're told that one in 625 infants suffer from cystic fibrosis were being given the frequency of these homozygous resistive phenotype in the population. This is representing Q square. So Q square is going to be equal to one divided by 625. So if we want to determine the frequency of the recessive or Q in the population, all we need to do is find the square root of both sides of this equation. So one divided by 100 by 625 is going to be equal to 0.0 16, find the square root of both sides. And we're going to obtain that Q or the frequency of the recessive AO is 0.4. So the correct answer for this question is going to be B 0.4. I really hope this helped and I hope to see you on the next video.

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