Hardy-weinberg formulas.

[DDS] Samer

Grind don't stop.
I do not understand when to use p+q=1 or p^2+2pq+q^2=1.

In the questions I've came across they usually use the words "alleles", "frequency", "individuals", "genotype", "phenotype". How do I know when to use which? It is really confusing me a lot.

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dawg289

5+ Year Member
I don't want to come across as harsh, but if you do not understand when to use p+q=1 or p^2+2qp+q^2=1, then you do not know how to do Hardy-weinberg problems.
If you're not familiar with the terms alleles, frequency, individuals, genotype, and phenotype, read a biology textbook on it. it should help a lot.

• StevenLuSL

7+ Year Member
For example, If the question says something like: "The allele frequency of the recessive allele is 0.4, it may ask you what the heterozygote frequency is for the population."

When you're given allele frequency, use the equation p+q=1----> q=0.4, and thus p=0.6
This means the heterozygote frequency (any time it asks you for frequency of the PHENOTYPE, you use p^2+2pq+q^2=1, note that a dominant phenotype would be p^2+2pq)
Now, back to my question, the heterozygote frequency would simply be 2pq---> 2(0.4)(0.6)= 0.48----> The heterozyge frequency would be 48%. If you were given a population size, the heterozygote number would be 48% multiplied by that population number.
Hope I helped! Also, dawg289 reiterates the importance of the Hardy Weinberg equation and should be the questions where you get free points.

• ahisma, loteyk and SXCoronado
S

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Master Yoda

7+ Year Member
I don't want to come across as harsh, but if you do not understand when to use p+q=1 or p^2+2qp+q^2=1, then you do not know how to do Hardy-weinberg problems.
If you're not familiar with the terms alleles, frequency, individuals, genotype, and phenotype, read a biology textbook on it. it should help a lot.
ouch. that was harsh. valkyrie08

Watch Craig Savage's videos on population genetics!

• [DDS] Samer and StevenLuSL

[DDS] Samer

Grind don't stop.
You guys helped a lot! Does anyone know where I can find some practice problems?

StevenLuSL

7+ Year Member
• [DDS] Samer