Textbook Question
The frequency of an autosomal recessive condition is 0.001 (1 in 1000) in a population.
What is the frequency of the mutant allele?
Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172
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Table of contents
- Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution64
- Ch. 2 - Transmission Genetics144
- Ch. 3 - Cell Division and Chromosome Heredity81
- Ch. 4 - Gene Interaction87
- Ch. 5 - Genetic Linkage and Mapping in Eukaryotes103
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages73
- Ch. 7 - DNA Structure and Replication71
- Ch. 8 - Molecular Biology of Transcription and RNA Processing79
- Ch. 9 - The Molecular Biology of Translation110
- Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization100
- Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination86
- Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage90
- Ch. 13 - Regulation of Gene Expression in Eukaryotes38
- Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics72
- Ch. 15 - Recombinant DNA Technology and Its Applications69
- Ch. 16 - Genomics: Genetics from a Whole-Genome Perspective49
- Ch. 17 - Organelle Inheritance and the Evolution of Organelle Genomes27
- Ch. 18 - Developmental Genetics43
- Ch. 19 - Genetic Analysis of Quantitative Traits66
- Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels105
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
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Sanders 3rd EditionCh. 20 - Population Genetics and Evolution at the Population, Species, and Molecular LevelsProblem 31c
Sanders 3rd EditionCh. 20 - Population Genetics and Evolution at the Population, Species, and Molecular LevelsProblem 31cChapter 20, Problem 31c
Albinism, an autosomal recessive trait characterized by an absence of skin pigmentation, is found in 1 in 4000 people in populations at equilibrium. Brachydactyly, an autosomal dominant trait producing shortened fingers and toes, is found in 1 in 6000 people in populations at equilibrium. For each of these traits, calculate the frequency of heterozygotes in the population
Verified step by step guidance1
Step 1: Understand the problem. Albinism is an autosomal recessive trait, meaning individuals with the condition have two copies of the recessive allele (aa). Brachydactyly is an autosomal dominant trait, meaning individuals with the condition have at least one dominant allele (Bb or BB). We are tasked with calculating the frequency of heterozygotes (Aa for albinism and Bb for brachydactyly) in the population.
Step 2: Use the Hardy-Weinberg equilibrium principle. For a population at equilibrium, the allele frequencies can be used to calculate genotype frequencies. The Hardy-Weinberg equation is p² + 2pq + q² = 1, where p is the frequency of the dominant allele, q is the frequency of the recessive allele, p² is the frequency of homozygous dominant individuals, 2pq is the frequency of heterozygotes, and q² is the frequency of homozygous recessive individuals.
Step 3: Calculate the allele frequencies for albinism. Since the frequency of individuals with albinism (aa) is given as 1 in 4000, this corresponds to q² = 1/4000. Solve for q, the frequency of the recessive allele, by taking the square root of q². Then, calculate p, the frequency of the dominant allele, using the relationship p + q = 1.
Step 4: Calculate the frequency of heterozygotes for albinism. Using the Hardy-Weinberg equation, the frequency of heterozygotes (Aa) is given by 2pq. Multiply the calculated values of p and q by 2 to find the heterozygote frequency for albinism.
Step 5: Repeat the process for brachydactyly. Since the frequency of individuals with brachydactyly (BB or Bb) is given as 1 in 6000, this corresponds to p² + 2pq = 1/6000. Use the Hardy-Weinberg equation to estimate p and q, and then calculate the frequency of heterozygotes (Bb) using 2pq.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hardy-Weinberg Principle
The Hardy-Weinberg Principle provides a mathematical framework for understanding genetic variation in a population at equilibrium. It states that allele and genotype frequencies will remain constant from generation to generation in the absence of evolutionary influences. This principle allows for the calculation of allele frequencies and the expected proportions of genotypes, including heterozygotes, based on observed trait frequencies.
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Hardy Weinberg
Autosomal Recessive Inheritance
Autosomal recessive inheritance refers to a pattern where two copies of a mutated gene are necessary for an individual to express a trait, such as albinism. In this case, individuals with one normal and one mutated allele (heterozygotes) do not exhibit the trait but can pass the mutated allele to their offspring. Understanding this inheritance pattern is crucial for calculating the frequency of heterozygotes in a population.
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Autosomal Dominant Inheritance
Autosomal dominant inheritance occurs when only one copy of a mutated gene is sufficient to express a trait, such as brachydactyly. Individuals with the dominant allele will show the trait, while those with two normal alleles will not. This concept is essential for determining the frequency of heterozygotes, as it influences the expected genotype ratios in the population based on the trait's prevalence.
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Related Practice
Textbook Question
In humans the presence of chin and cheek dimples is dominant to the absence of dimples, and the ability to taste the compound PTC is dominant to the inability to taste the compound. Both traits are autosomal, and they are unlinked. The frequencies of alleles for dimples are D = 0.62 and d = 0.38. For tasting, the allele frequencies are T = 0.76 and t = 0.24.
What are the expected frequencies of the four possible phenotype combinations: dimpled tasters, undimpled tasters, dimpled nontasters, and undimpled nontasters?
Textbook Question
Albinism, an autosomal recessive trait characterized by an absence of skin pigmentation, is found in 1 in 4000 people in populations at equilibrium. Brachydactyly, an autosomal dominant trait producing shortened fingers and toes, is found in 1 in 6000 people in populations at equilibrium. For each of these traits, calculate the frequency of the recessive allele at the locus
Textbook Question
Albinism, an autosomal recessive trait characterized by an absence of skin pigmentation, is found in 1 in 4000 people in populations at equilibrium. Brachydactyly, an autosomal dominant trait producing shortened fingers and toes, is found in 1 in 6000 people in populations at equilibrium. For each of these traits, calculate the frequency of the dominant allele at the locus
Textbook Question
Albinism, an autosomal recessive trait characterized by an absence of skin pigmentation, is found in 1 in 4000 people in populations at equilibrium. Brachydactyly, an autosomal dominant trait producing shortened fingers and toes, is found in 1 in 6000 people in populations at equilibrium. For each of these traits, calculate the frequency of For albinism only, what is the frequency of mating between heterozygotes?
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Textbook Question
The frequency of an autosomal recessive condition is 0.001 (1 in 1000) in a population.
What is the frequency of carriers of the mutant allele?