Genetic Analysis 20.1 predicts the number of individuals expected to have the blood group genotypes MM, MN, and NN. Perform a chi-square analysis using the number of people observed and expected in each blood-type category, and state whether the sample is in H-W equilibrium.

Verified step by step guidance

1. Step 1: Begin by calculating the allele frequencies for the M and N alleles. Use the observed genotype counts to determine the frequency of each allele. For example, if the observed counts are given for MM, MN, and NN, calculate the frequency of M as (2 * MM count + MN count) / (2 * total individuals) and the frequency of N as 1 - frequency of M.
2. Step 2: Use the Hardy-Weinberg equilibrium principle to calculate the expected genotype frequencies. The expected frequency of MM is p^2, the expected frequency of MN is 2pq, and the expected frequency of NN is q^2, where p is the frequency of the M allele and q is the frequency of the N allele.
3. Step 3: Multiply the expected genotype frequencies by the total number of individuals in the sample to calculate the expected counts for each genotype (MM, MN, NN). For example, expected count for MM = p^2 * total individuals.
4. Step 4: Perform the chi-square analysis using the formula χ² = Σ((observed - expected)^2 / expected), where the summation is over all genotype categories (MM, MN, NN). For each genotype, calculate the difference between the observed and expected counts, square it, divide by the expected count, and sum these values.
5. Step 5: Compare the calculated chi-square value to the critical value from the chi-square distribution table at the appropriate degrees of freedom (df = number of categories - 1) and significance level (commonly 0.05). If the chi-square value is less than the critical value, the sample is in Hardy-Weinberg equilibrium; otherwise, it is not.

Key Concepts

Blood Group Genotypes

Blood group genotypes refer to the genetic variations that determine an individual's blood type, specifically the presence of alleles M and N. The genotypes MM, MN, and NN correspond to different combinations of these alleles, which are inherited from parents. Understanding these genotypes is crucial for predicting the distribution of blood types in a population.

Chi-Square Analysis

Chi-square analysis is a statistical method used to compare observed data with expected data to determine if there is a significant difference between them. In genetics, it helps assess whether the distribution of genotypes in a sample fits the expected ratios under Hardy-Weinberg equilibrium. The chi-square statistic is calculated using the formula: χ² = Σ((O - E)² / E), where O is the observed frequency and E is the expected frequency.

Hardy-Weinberg Equilibrium

Hardy-Weinberg equilibrium is a principle that describes the genetic variation in a population that remains constant from one generation to the next in the absence of evolutionary influences. For a population to be in H-W equilibrium, certain conditions must be met, including no mutation, random mating, no gene flow, infinite population size, and no selection. Deviations from this equilibrium can indicate evolutionary changes or influences affecting the population.