## Can you help me with Hardy-Weinberg Problems?

Debate and discussion of any biological questions not pertaining to a particular topic.

betweenthepages
Garter
Posts: 1
Joined: Tue Nov 09, 2010 4:31 pm

### Can you help me with Hardy-Weinberg Problems?

I want more general help than with a specific problem. I don't really understand how to do HW problems when they give you phenotype.
For example: if it tells me that 360 out of 1,000 in a population display the recessive phenotype, how would I find the numbers of individuals expected to be homozygous dominant and heterozygous for the trait?
I tried making the 360 => .36 in the P+Q=1 equation, but then I don't know how to find the 2PG (for the hets) because the numbers will no longer add up to 1 in the p^2+2pq+q^2 equation. Is .36 really the q^2? And then I have to find normal q by square rooting? Or am I on entirely the wrong track?

Also: if they tell me that 510 out of 1,000 show the dominant phenotype, how do I find the numbers of individuals for each genotype?

JackBean
Inland Taipan
Posts: 5694
Joined: Mon Sep 14, 2009 7:12 pm
I don't see any problem. q2 is 0.36, so q is 0.6; from this you calculate p from p + q = 1; so you get p = 0.4 and then you just put the numbers into p2 + 2pq + q2 = 1, which works for me.
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

JackBean
Inland Taipan
Posts: 5694
Joined: Mon Sep 14, 2009 7:12 pm
in the other one, I think I would work like this:

0.51 = p2 + 2pq /(from p + q = 1)
0.51 = p2 + 2p*(1-p) = p2 + 2p - 2p2 = 2p - p2

so, you need to solve that equation...
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.

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