This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Biochemistry
Creatinine is formed from 
Select and explain. 
A. Glycine, B. Lysine, C. Leucine, D. Histamine
A: Glycine
Answer: A: Glycine 
Explanation: Creatinine and creatine are synthesized from glycine, arginine, and methionine. Synthesis of creatine and creatinine Creatine and creatinine are not amino acids, but specialized products of amino acids. Creatine is synthesized from glycine, arginine, and methionine. The synthesis stas with the formation of guanidinoacetate from glycine and arginine in the kidney. Fuher reactions take place in the liver and muscle. REF: Lippincott book of biochemistry 6th ed.