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
2. Mendel's Laws of Inheritance
Pedigrees
2:27 minutes
Problem 47b
Textbook Question
Textbook QuestionThe accompanying pedigree shows a family in which one child (II-1) has an autosomal recessive condition. On the basis of this fact alone, provide the following information.
What is the probability that all three of the children in generation II who have the dominant phenotype are Aa?
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Autosomal Recessive Inheritance
Autosomal recessive inheritance occurs when a trait is expressed only when an individual has two copies of the recessive allele (aa). Carriers, who have one dominant allele and one recessive allele (Aa), do not express the trait but can pass the recessive allele to their offspring. In the context of the pedigree, understanding this inheritance pattern is crucial for determining the genotypes of the children.
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Autosomal Pedigrees
Genotype Probability Calculation
Calculating genotype probabilities involves using the principles of Mendelian genetics to determine the likelihood of specific genotypes in offspring based on the genotypes of the parents. In this case, knowing that the child with the autosomal recessive condition is aa allows us to infer the possible genotypes of the parents and subsequently calculate the probability that the children with the dominant phenotype are heterozygous (Aa).
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Probability
Phenotype vs. Genotype
Phenotype refers to the observable traits of an organism, while genotype refers to the genetic makeup that determines those traits. In this question, the dominant phenotype could be expressed by either homozygous dominant (AA) or heterozygous (Aa) individuals. Understanding the distinction between these terms is essential for accurately assessing the probability of the children being Aa given their dominant phenotype.
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Gamete Genotypes
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