In the Hardy-Weinberg formula, what does p² represent?
A frequency of heterozygotes
B frequency of the recessive allele
C frequency of the homozygous dominants
D frequency of the dominant allele
The correct answer and explanation is :
The correct answer is C: frequency of the homozygous dominants.
The Hardy-Weinberg formula is a principle in population genetics used to calculate the genetic variation in a population at equilibrium. It is represented by the equation:
[
p^2 + 2pq + q^2 = 1
]
Where:
- ( p ) is the frequency of the dominant allele in the population.
- ( q ) is the frequency of the recessive allele in the population.
- ( p^2 ) represents the frequency of individuals who are homozygous dominant (having two dominant alleles, ( AA )).
- ( 2pq ) represents the frequency of individuals who are heterozygous (having one dominant allele and one recessive allele, ( Aa )).
- ( q^2 ) represents the frequency of individuals who are homozygous recessive (having two recessive alleles, ( aa )).
Explanation:
To understand what ( p^2 ) represents, let’s break it down:
- Homozygous Dominant (AA): These individuals have two copies of the dominant allele. In the Hardy-Weinberg equation, the probability that an individual inherits two dominant alleles (one from each parent) is ( p \times p ), or ( p^2 ). This is because the frequency of the dominant allele in the population is represented by ( p ), and since both alleles are dominant, the probability of both parents passing on the dominant allele to their offspring is ( p \times p = p^2 ). Hence, ( p^2 ) represents the frequency of homozygous dominant individuals in the population.
- Heterozygous (Aa): The probability of an individual being heterozygous (having one dominant allele and one recessive allele) is represented by ( 2pq ), because the individual could inherit the dominant allele from one parent and the recessive allele from the other, or vice versa.
- Homozygous Recessive (aa): The frequency of individuals who are homozygous recessive is represented by ( q^2 ), as both alleles must be recessive.
Thus, ( p^2 ) corresponds to the frequency of homozygous dominant individuals in a population, making option C the correct answer.