A total of 1000 members of a Central American population are typed for the ABO blood group. In the sample, 421 have blood type A, 168 have blood type B, 336 have blood type O, and 75 have blood type AB. Use this information to determine the frequency of ABO blood group alleles in the sample.

Verified step by step guidance

1. Identify the alleles involved in the ABO blood group system: IA, IB, and i.
2. Use the given blood type counts to set up equations based on the Hardy-Weinberg principle. For example, the frequency of blood type A (p^2 + 2pq) is related to the alleles IA and i.
3. Calculate the frequency of each blood type: A, B, O, and AB, by dividing the number of individuals with each blood type by the total population (1000).
4. Set up equations for each blood type using the allele frequencies: p^2 + 2pq for type A, q^2 + 2pq for type B, r^2 for type O, and 2pq for type AB, where p, q, and r are the frequencies of IA, IB, and i respectively.
5. Solve the system of equations to find the allele frequencies p, q, and r.

Key Concepts

ABO Blood Group System

The ABO blood group system is determined by the presence of antigens on the surface of red blood cells, specifically A and B antigens. There are four main blood types: A, B, AB, and O, which correspond to different combinations of these antigens. Blood type A has A antigens, type B has B antigens, type AB has both, and type O has neither. Understanding this system is crucial for analyzing allele frequencies in a population.

Allele Frequency

Allele frequency refers to how often a particular allele appears in a population compared to other alleles for the same gene. It is calculated by dividing the number of copies of the allele by the total number of alleles in the population. In the context of the ABO blood group, allele frequencies can be determined by counting the occurrences of each blood type and translating these into the corresponding alleles (A, B, and O).

Hardy-Weinberg Equilibrium

The Hardy-Weinberg equilibrium is a principle that describes the genetic variation in a population that is not evolving. It provides a mathematical model to predict allele and genotype frequencies under certain conditions, such as no mutation, migration, or selection. This concept is essential for understanding how allele frequencies can be expected to behave in a stable population, allowing for comparisons with observed frequencies to identify evolutionary changes.