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
Inheritance in Diploids and Haploids
3:03 minutes
Problem 2b
Textbook Question
Textbook QuestionHomocystinuria is a rare autosomal recessive condition on the RUSP list of conditions screened by newborn genetic testing. The condition results from a mutation that blocks the degradation of the amino acid methionine. The absence of a critical enzyme causes the buildup of the compound homocysteine, which is one of the intermediate compounds in the methionine breakdown pathway. Homocystinuria causes mental impairment, heart problems, seizures, eye abnormalities, and a number of other symptoms that shorten life if not treated. The condition is treated by a specialized diet that is low in methionine and by the ingestion of several supplements.
Why do you think eating a low-methionine diet is critical to controlling homocystinuria?
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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 is a genetic pattern where two copies of a mutated gene, one from each parent, are required for an individual to express a trait or condition. In the case of homocystinuria, both parents must carry the mutation for their child to be affected. This means that even if a parent is a carrier (having one mutated gene), they typically do not show symptoms, making genetic screening important for early detection.
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Autosomal Pedigrees
Methionine Metabolism
Methionine metabolism refers to the biochemical processes that break down the amino acid methionine into other compounds, including homocysteine. In individuals with homocystinuria, a mutation leads to the deficiency of a critical enzyme necessary for this pathway, resulting in the accumulation of homocysteine. Understanding this metabolic pathway is essential for grasping why dietary management is crucial in controlling the condition.
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Translation initiation
Dietary Management in Genetic Disorders
Dietary management in genetic disorders involves modifying a patient's diet to mitigate the effects of a genetic condition. For homocystinuria, a low-methionine diet is critical because it reduces the substrate available for the harmful buildup of homocysteine. This dietary intervention, combined with supplements, helps manage symptoms and improve the quality of life for affected individuals, highlighting the importance of nutrition in genetic health.
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Descriptive Genetics
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