Hardy Weinberg equation , Simple and Conceptual description with solved exercise

Simple and Conceptual explanation with solved exercise


Hardy Weinberg Law –




• G.H. Hardy (English mathematician,1908) & German Physician,
W. Weinberg (independent work)
• equilibrium is established between frequencies of allele in
random mating large population and these gene frequency
remain constant from generation to generation.
• This law is applicable when mutation, selection & migration, are
absent.
Hardy-Weinberg Assumption
1. Individuals must randomly mate
2. No migration (No gene flow)
3. No mutation
4. Genes are autosomal
5. No selection
6. Population must be very large
Hardy Weinberg theorem or Hardy Weinberg law
p2 +2pq +q2 = 1 (A = p, a = q, p+q = 1)
AA Aa aa

, ➢ frequency of A = P
• Frequency of Homozygous dominant (AA)=P2
➢ frequency of a = q
• frequency of homozygous recessive aa=q2
➢ frequency of Aa = 2pq
The frequency of different genotype produced due to random mating
will depend upon the gene frequency and equilibrium is stablished
after one single generation of random mating.
Note: changes in allele frequency are the genetic basis of
evolution.
1. In a random large population frequency of recessive
phenotype is 0.36. What is the frequency of heterozygous
genotype?
q2 = 0.36
q = 0.6
p=1–q
p = 1 – 0.6
= 0.4
Frequency of heterozygotes = 2pq
=2x0.6x0.4
=0.48
=48%
2. In the Caucasian population of the US, 1 in 2500 babies is
affected by a recessive condition – cystic fibrosis. In this
population, the frequency of the dominant allele is
(a) 0.02
(b) 0.36
(c) 0.56