In humans the presence of chin and cheek dimples is dominant to t...

Question

In humans the presence of chin and cheek dimples is dominant to the absence of dimples, and the ability to taste the compound PTC is dominant to the inability to taste the compound. Both traits are autosomal, and they are unlinked. The frequencies of alleles for dimples are D = 0.62 and d = 0.38. For tasting, the allele frequencies are T = 0.76 and t = 0.24.What are the expected frequencies of the four possible phenotype combinations: dimpled tasters, undimpled tasters, dimpled nontasters, and undimpled nontasters?

Accepted Answer

Hello, everyone and welcome to today's video. So, cystic fibrosis is a recessive genetic disease that is caused by mutation on both C F T R A. So the frequency of the mutated Aleo in a population was found to be 0.1. So what is the genotype frequency of the carriers? So as answer choice A we have 0.1 as answer choice B we have 0.198 as answer choice B we have 0.9801. And as answer choice C we have one. Now let's first determine or realize that cystic fibrosis is going to be a recessive disease, meaning that we need two copies of this recessive allele in order for it to be expressed in the phenotype. So we are being asked for the frequency of the carriers. These carriers are going to have one dominant and one recessive ali which is going to make them carry the disease but not express it. This is why they're called carriers. So this is going to be the heteros. Now, in the Hardy Weinberg equation, we can determine the frequency of heterozygous or these carriers using two times P times Q. So we can use these little formula or this expression in order to find this frequency. So it's going to be two times P which is going to be the frequency of the non mutated A which is going to be zero point 99. And then the frequency of the mutated all is going to be 0.1. We know that this is 0.99. Because if the frequency of the mutated AO is 0.1, then the frequency of the non mutated AO is going to be all the rest or 0.99. So this is why we put this for P. Now, when we make this multiplication, we're going to obtain a frequency of 0. 98. And this is going to be represented by answer choice B 0.1 98. I really hope this video helped you and I hope to see you on the next one.

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