Basic Calculation of Allele and Genotype Frequencies PDF

**Exercise 1: Basic Calculation of Allele and Genotype Frequencies (Easy)** **Exercise 1: Basic Calculation of Allele and Genotype Frequencies (Easy)** **Objective:** Calculate allele and genotype frequencies in a simple population. **Instructions:** 1. Consider a population of 50 individuals w...

**Exercise 1: Basic Calculation of Allele and Genotype Frequencies (Easy)** **Exercise 1: Basic Calculation of Allele and Genotype Frequencies (Easy)** **Objective:** Calculate allele and genotype frequencies in a simple population. **Instructions:** 1. Consider a population of 50 individuals with the following genotypes: - 20 individuals with genotype AA - 20 individuals with genotype Aa - 10 individuals with genotype aa 2. Calculate the allele frequencies of A and a. 3. Calculate the genotype frequencies of AA, Aa, and aa. **Questions:** 1. What are the frequencies of alleles A and a? 2. What are the frequencies of genotypes AA, Aa, and aa? **ANSWERS** 1. **What are the frequencies of alleles A and a?** - **Number of A alleles:** - Each AA individual has 2 A alleles: ( 20 \\times 2 = 40 ) - Each Aa individual has 1 A allele: ( 20 \\times 1 = 20 ) - Total A alleles: ( 40 + 20 = 60 ) - **Number of a alleles:** - Each aa individual has 2 a alleles: ( 10 \\times 2 = 20 ) - Each Aa individual has 1 a allele: ( 20 \\times 1 = 20 ) - Total a alleles: ( 20 + 20 = 40 ) - **Total number of alleles:** - ( 60 + 40 = 100 ) - **Allele frequencies:** - Frequency of A (( p )): ( \\frac{60}{100} = 0.6 ) - Frequency of a (( q )): ( \\frac{40}{100} = 0.4 ) 2. **What are the frequencies of genotypes AA, Aa, and aa?** - Frequency of AA: ( \\frac{20}{50} = 0.4 ) - Frequency of Aa: ( \\frac{20}{50} = 0.4 ) - Frequency of aa: ( \\frac{10}{50} = 0.2 ) **Exercise 2: Applying Hardy-Weinberg Equilibrium (Intermediate)** 1. Consider a population of 200 individuals with the following genotypes: - 100 individuals with genotype AA - 80 individuals with genotype Aa - 20 individuals with genotype aa 2. Calculate the allele frequencies of A and a. 3. Calculate the expected genotype frequencies under Hardy-Weinberg equilibrium. 4. Compare the observed genotype frequencies with the expected genotype frequencies. **Questions:** 1. What are the allele frequencies of A and a? 2. What are the expected genotype frequencies of AA, Aa, and aa under Hardy-Weinberg equilibrium? 3. Is the population in Hardy-Weinberg equilibrium? Explain your reasoning. **ANSWERS** 1. **What are the allele frequencies of A and a?** - **Number of A alleles:** - Each AA individual has 2 A alleles: ( 100 \\times 2 = 200 ) - Each Aa individual has 1 A allele: ( 80 \\times 1 = 80 ) - Total A alleles: ( 200 + 80 = 280 ) - **Number of a alleles:** - Each aa individual has 2 a alleles: ( 20 \\times 2 = 40 ) - Each Aa individual has 1 a allele: ( 80 \\times 1 = 80 ) - Total a alleles: ( 40 + 80 = 120 ) - **Total number of alleles:** - ( 280 + 120 = 400 ) - **Allele frequencies:** - Frequency of A (( p )): ( \\frac{280}{400} = 0.7 ) - Frequency of a (( q )): ( \\frac{120}{400} = 0.3 ) 2. **What are the expected genotype frequencies of AA, Aa, and aa under Hardy-Weinberg equilibrium?** - ( p\^2 ) (AA): ( 0.7\^2 = 0.49 ) - ( 2pq ) (Aa): ( 2 \\times 0.7 \\times 0.3 = 0.42 ) - ( q\^2 ) (aa): ( 0.3\^2 = 0.09 ) 3. **Is the population in Hardy-Weinberg equilibrium? Explain your reasoning.** - **Expected number of individuals:** - AA: ( 0.49 \\times 200 = 98 ) - Aa: ( 0.42 \\times 200 = 84 ) - aa: ( 0.09 \\times 200 = 18 ) - **Comparison with observed numbers:** - Observed AA: 100, Expected AA: 98 - Observed Aa: 80, Expected Aa: 84 - Observed aa: 20, Expected aa: 18 - The observed genotype frequencies (0.5, 0.4, 0.1) are close to the expected frequencies (0.49, 0.42, 0.09), indicating the population is approximately in Hardy-Weinberg equilibrium. **Exercise 3: Analyzing a Real-World Population (Advanced)** **nstructions:** 1. Obtain data from a real-world population (e.g., a specific animal species in a particular region) with the following genotypes: - Homozygous dominant (AA) - Heterozygous (Aa) - Homozygous recessive (aa) 2. Calculate the allele frequencies of A and a. 3. Calculate the observed genotype frequencies. 4. Calculate the expected genotype frequencies under Hardy-Weinberg equilibrium. 5. Compare the observed and expected genotype frequencies. 6. Discuss any deviations from Hardy-Weinberg equilibrium and potential factors causing these deviations (e.g., selection, mutation, migration, genetic drift). **Questions:** 1. What are the allele frequencies of A and a in the real-world population? 2. What are the observed and expected genotype frequencies of AA, Aa, and aa? 3. Is the population in Hardy-Weinberg equilibrium? If not, what factors might be causing deviations? **ANSWER** 1. **What are the allele frequencies of A and a in the real-world population?** - This will depend on the specific data obtained from the real-world population. Students should follow the same steps as in the previous exercises to calculate the allele frequencies. 2. **What are the observed and expected genotype frequencies of AA, Aa, and aa?** - Observed genotype frequencies should be calculated based on the real-world data. - Expected genotype frequencies should be calculated using the Hardy-Weinberg equilibrium formula: ( p\^2 ), ( 2pq ), and ( q\^2 ). 3. **Is the population in Hardy-Weinberg equilibrium? If not, what factors might be causing deviations?** - Students should compare the observed and expected genotype frequencies. - If there are significant deviations, students should discuss potential factors such as selection, mutation, migration, genetic drift, or non-random mating that might be causing these deviations. These answers should help students understand how to calculate and interpret allele and genotype frequencies, as well as how to verify Hardy-Weinberg equilibrium in different scenarios. 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