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
Free SH group is present in 
Select and explain. 
A. Cysteine, B. Methionine, C. Taurine, D. Homoserine
A: Cysteine
Answer: A: Cysteine 
Explanation: 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