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
17. Mutation, Repair, and Recombination
Types of Mutations
Problem 12c
Textbook Question
If you were to look up Gaucher disease on the OMIM website, you would see that there are three major types, designated Type I (OMIM 230800), Type II (OMIM 230900), and Type III (OMIM 231000). All three types are mutations of the gene for acid-β-glucosidase, encoded on chromosome 1. Different mutations of this gene produce the three types of Gaucher disease that differ somewhat in their symptoms and disease severity.
For each mutation, speculate about whether the acid-β-glucosidase enzyme is merely reduced in function or whether its production is eliminated, and explain why.
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span>Step 1: Understand the role of acid-β-glucosidase enzyme. This enzyme is crucial for breaking down glucocerebroside into glucose and ceramide. A deficiency or malfunction can lead to the accumulation of glucocerebroside, causing Gaucher disease.</span
span>Step 2: Consider the genetic mutations involved. Different mutations in the gene encoding acid-β-glucosidase can lead to varying levels of enzyme activity. Some mutations might result in a partially functional enzyme, while others could lead to a complete loss of enzyme production.</span
span>Step 3: Analyze the symptoms associated with each type of Gaucher disease. Type I is typically less severe and non-neuropathic, suggesting that some enzyme activity might be retained. In contrast, Types II and III are more severe and involve neurological symptoms, indicating a more significant reduction or complete loss of enzyme function.</span
span>Step 4: Speculate on the nature of the mutations. For Type I, mutations might lead to a reduced function of the enzyme, where the enzyme is still produced but is less effective. For Types II and III, mutations might result in a more drastic reduction in enzyme activity or complete elimination of enzyme production.</span
span>Step 5: Consider the biochemical impact of these mutations. Reduced enzyme function could be due to missense mutations that alter the enzyme's active site, while nonsense or frameshift mutations could lead to a truncated, non-functional enzyme, or no enzyme production at all.</span
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Gaucher Disease Types
Gaucher disease is a genetic disorder caused by mutations in the gene encoding acid-β-glucosidase, leading to three major types: Type I, Type II, and Type III. Each type is characterized by varying symptoms and severity, with Type I being the most common and least severe, while Type II is the most severe and often fatal in infancy. Understanding these distinctions is crucial for analyzing the functional impact of specific mutations on the enzyme.
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Acid-β-glucosidase Function
Acid-β-glucosidase is an enzyme responsible for breaking down glucocerebroside into glucose and ceramide. In Gaucher disease, mutations can lead to either a reduction in enzyme activity or complete loss of function. The degree of enzyme activity directly correlates with the severity of the disease, making it essential to assess whether mutations result in diminished function or total enzyme absence.
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Genetic Mutations and Enzyme Activity
Genetic mutations can affect protein function in various ways, including missense mutations that alter amino acids, nonsense mutations that create premature stop codons, or frameshift mutations that disrupt the reading frame. These changes can lead to reduced enzyme activity or complete loss of production. Speculating on the nature of these mutations in Gaucher disease helps in understanding the clinical manifestations and potential treatment strategies.
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