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
2:05 minutes
Problem 14e
Textbook Question
Textbook QuestionNail–patella syndrome is an autosomal disorder affecting the shape of nails on fingers and toes as well as the structure of kneecaps. The pedigree below shows the transmission of nail–patella syndrome in a family along with ABO blood type.
Explain why III-6 has nail–patella syndrome and III-8 does not. Give genotypes for these two individuals.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Autosomal Dominant Inheritance
Nail-patella syndrome is inherited in an autosomal dominant manner, meaning that only one copy of the mutated gene from an affected parent can cause the disorder. This type of inheritance typically results in the condition appearing in every generation, as affected individuals have a 50% chance of passing the trait to their offspring.
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Variations on Dominance
Genotype and Phenotype
The genotype refers to the genetic makeup of an individual, while the phenotype is the observable expression of that genotype. In the case of nail-patella syndrome, an individual with the genotype 'Nn' (where 'N' is the normal allele and 'n' is the mutated allele) will express the syndrome, whereas an individual with the genotype 'NN' will not.
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Gamete Genotypes
Pedigree Analysis
Pedigree analysis is a tool used to track the inheritance patterns of traits within a family. By examining the pedigree provided, one can determine the genotypes of individuals based on their affected or unaffected status, helping to explain why certain family members, like III-6, exhibit the syndrome while others, like III-8, do not.
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Pedigree Flowchart
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