Hardy-Weinberg Equilibrium

[TXpredent]

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Hi yall,

I'm very confused about how to tell when the question is giving p or p^2. For example, "The frequency for the allele in cystic fibrosis, an autosomal recessive trait, is 1/2500, what is the heterozygote frequency?" I thought since it was the frequency it was definitely p. So I went and solved for the 2pq part using p. However, they gave us p^2 here 🙁

Can anyone help me tell the difference? Thanks!

 

[Muelitas]

Yeah, It's a little confusing at times..

I believe that if the problem states a frequency for a population (for ex: Cystic Fibrosis), then they are talking of the big picture: P^2 or Q^2.

Now, if they are stating a frequency for a few alleles, then you start by p+q=1 and work your way up to P^2+2pq+Q^2=1 in order to find the frequency for a population.

That's how I've thought about it and it helps me remember where I should start.