Why are X rays more potent mutagens than UV radiation?
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 14d
Textbook Question
Several types of mutation are identified and described in the chapter. These include (1) promoter mutation, (2) splice site mutation, (3) missense mutation, (4) frameshift mutation, and 5) nonsense mutation. Match the following mutation descriptions with the type(s) of mutations listed above. More than one mutation type might match a description.
A mutation that produces a protein that is shorter than the wild-type protein but does not have any amino acid changes in the portion produced.

1
Understand the problem: The question asks us to identify the type(s) of mutation that result in a protein shorter than the wild-type protein, without any amino acid changes in the portion of the protein that is produced.
Review the mutation types: (1) Promoter mutation affects transcription initiation, (2) Splice site mutation affects RNA splicing, (3) Missense mutation changes one amino acid, (4) Frameshift mutation alters the reading frame, and (5) Nonsense mutation introduces a premature stop codon.
Focus on the key description: The protein is shorter, which suggests that translation was terminated early. This aligns with a nonsense mutation, as it introduces a stop codon prematurely.
Verify that there are no amino acid changes in the portion of the protein produced: This confirms that the mutation does not alter the sequence of the translated portion, which is consistent with a nonsense mutation.
Conclude that the mutation described matches a nonsense mutation, as it produces a truncated protein without altering the amino acid sequence of the translated portion.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nonsense Mutation
A nonsense mutation is a type of point mutation where a single nucleotide change results in a premature stop codon in the protein sequence. This leads to the production of a truncated protein that is shorter than the wild-type protein. Nonsense mutations can significantly affect protein function, often resulting in loss of activity or stability.
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Frameshift Mutation
Frameshift mutations occur when nucleotides are inserted or deleted from the DNA sequence, causing a shift in the reading frame of the codons. This alteration can lead to a completely different translation from the original, often resulting in a nonfunctional protein. While frameshift mutations typically produce longer or shorter proteins, they can also lead to premature stop codons.
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Missense Mutation
A missense mutation is a type of mutation where a single nucleotide change results in the substitution of one amino acid for another in the protein sequence. While this can lead to a functional protein, it may also alter the protein's activity or stability. However, in the context of the question, a missense mutation would not produce a shorter protein without amino acid changes in the remaining sequence.
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