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
Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
21. Population Genetics
Hardy Weinberg
Problem 32a
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?

1
Understand that the problem involves Hardy-Weinberg equilibrium, which is used to calculate allele frequencies in a population. The frequency of the autosomal recessive condition (q²) is given as 0.001.
Recall the Hardy-Weinberg equation: p² + 2pq + q² = 1, where p is the frequency of the dominant allele, q is the frequency of the recessive allele, p² represents the frequency of homozygous dominant individuals, 2pq represents the frequency of heterozygous individuals, and q² represents the frequency of homozygous recessive individuals.
To find the frequency of the mutant allele (q), take the square root of q². Use the formula: .
Substitute the given value of q² (0.001) into the formula: . This will give the value of q, which represents the frequency of the mutant allele.
Conclude that the calculated value of q represents the frequency of the mutant allele in the population. Ensure that the result is expressed as a decimal or percentage, depending on the context of the problem.

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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 allele and genotype frequencies in a population at equilibrium. It states that in a large, randomly mating population with no evolutionary influences, the frequencies of alleles and genotypes will remain constant from generation to generation. This principle is essential for calculating allele frequencies, particularly in the context of autosomal recessive conditions.
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Allele Frequency
Allele frequency refers to how often a particular allele appears in a population compared to other alleles for the same gene. In the case of an autosomal recessive condition, the frequency of the mutant allele can be derived from the frequency of affected individuals. Understanding allele frequency is crucial for predicting the likelihood of genetic conditions within a population.
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Autosomal Recessive Inheritance
Autosomal recessive inheritance occurs when two copies of a mutant allele are necessary for an individual to express a trait or condition. In a population, the frequency of affected individuals can be used to estimate the frequency of the recessive allele using the formula q^2 = frequency of affected individuals, where q represents the frequency of the recessive allele. This concept is fundamental for solving questions related to genetic conditions and their prevalence.
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