Hardy weinberg equation

[Mp07d]

Hey guys, I always get confused as to what exactly I have to use when im doing HW.. for example using q vs q^2. Can someone please give me a quick example explaining the differences between p+q and (p+q)^2

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[SNDO]

I love Hardy-Weinberg!

p = dominant allele (example: A)
q = recessive allele (example: a)
p+q=1


p^2 = dominant homozygous (AA)
2pq = heterozygous (Aa)
q^2 = homozygous recessive (aa)
p^2 + 2pq + q^2 = 1

Hardy-Weinberg equations have to do with frequencies of the dominant and recessive alleles and the frequencies of AA, Aa, aa in a given population.

Anyone feel free to add or fix this!

 

[flodhi1]

Hey guys, I always get confused as to what exactly I have to use when im doing HW.. for example using q vs q^2. Can someone please give me a quick example explaining the differences between p+q and (p+q)^2

Okay first of all q is the allele for recessive gene.
q^2 is the recessive phenotype
p is the allele for the dominant gene
p^2 is the dominant phenotype

So let's say you have an autosomal disease where A represents the dominant allele for hmm normal hemoglobin but a represents the recessive allele for sickle cell anemia....

So a would be = q
aa which would be the sickle cell disease or the percent of people that have the sickle cell disease = q^2
A would be =p
AA would be the phenotype for the individuals that are homozygous dominant for normal and this = p^2
2pq would be the heterozygous guys which would be NORMAL since p is dominant over q and for q that is the recessive allele to exhibit the disease you much be qq / (aa) / q^2 👍

 

[Mp07d]

ok so basically if they say.... there is a recessive disease that affects 16/400 people - that would be the q^2 not the q, since its the frequency of the phenotype, right?......

so q^2 = 1/25
and q= 1/5=0.2

 

[justhanging]

I had the same difficulty. Don't worry if q or p is recessive or dominant that's arbitrary. q is the frequency of the allele and q^2 is the frequency of phenotype or trait, so your right. The way I remember it is just to use probability, if the probability of getting r from a gene pool is 0.2 then getting rr the recessive phenotype should be 0.2*0.2 (or q^2).