This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'A mutation that converts an amino acid codon to a stop codon is a: \nSelect and explain. \nA. Nonsense mutation, B. Transversion, C. Silent mutation, D. Frame shift mutation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Changes one codon for an amino acid into another codon for that same amino acid - Silent mutation\nCodon for one amino acid is changed into a codon of another amino acid - Missense mutation\nCodon for one amino acid is changed into a translation termination codon -\xa0Non-sense mutation\nReading frame changes downstream to the mutant site -\xa0Frameshift mutation.\nA purine base replaced by another pyrimidine,\xa0 or\xa0 pyrimidine\xa0 replaced\xa0 by\xa0 another\xa0purine -Transversion.\n\nKey Concept\nNonsense mutation\nA coding codon mutated to a nonsense codon result in premature termination of polypeptide chain.', 'role': 'assistant'}]