This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Basics of amino acids, Subject name: Biochemistry
[{'content': 'Free SH group is present in \nSelect and explain. \nA. Cysteine, B. Methionine, C. Taurine, D. Homoserine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: This is a tricky question. Option a, b and c have sulphur. But, only cysteine contains SH group. EXTRA EDGE:- Sulphur containing amino acids: Cysteine Methionine Homocysteine Taurine Sulfhydryl/thiol group-containing amino acids: Cysteine Homocysteine Sulfhydryl/thiol group-containing proteinogenic amino acids: Cysteine', 'role': 'assistant'}]