Hardy-Weinberg Equilibrium Problems
p is the frequency of the dominant allele in the population
q is the frequency of the recessive allele in the population
p2 is the frequency of the homozygous dominant genotype
q2 is the frequency of the homozygous recessive genotype
2pq is the frequency of the heterozygous genotype
p + q = 1
p2 + 2pq + q2 = 1 Find q2 ï q ï p ï p2 ï 2pq
A rare disorder of cystic fibrosis (characterized by abnormal transport ofchloride and sodium across an epithelium, leading to thick, viscous secretions) occurs every 1 in 3,300 births. To express this trait one must be homozygous recessive (ff).
The cystic fibrosis allele is represented by f. The normal allele is F. Suppose both parents have alleles Ff. The possible combinations of alleles in the children are FF, Ff, Ff and ff. The alleles ff will cause the disease. So, although the parents do not have cystic fibrosis, they can produce children with the disease. The parents are called 'carriers' of the disease
What is the frequency of the population that carries the trait? (Ff)