Cysteine is synthesized from: (A) Methionine, (B) Arginine, (C) Histidine, (D) Lysine
Answer is A. Methionine is first conveed to active methionine and then it is conveed to cysteine on combining with serine.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 217, Fig 16.14, 16.15.