This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Proteins and Amino Acids, Subject name: Biochemistry
Guanido acetic acid is formed in.... from.... 
Select and explain. 
A. Kidney; Arginine + glycine, B. Liver; Methionine + glycine, C. Liver; Cysteine + arginine, D. Muscle; Citrulline + aspartate
A: Kidney; Arginine + glycine
Answer: A: Kidney; Arginine + glycine 
Explanation: Ans. A. Kidney; Arginine + GlycineSteps of synthesis of CreatinineStep I Glycine Arginine Amido TransferaseFirst step in the Kidney.Guanidino group of Arginine is transferred to Glycine to form Guanidino Acetic Acid.Step II Guanidino Acetate Methyl TransferaseSecond step in the LiverCreatine is formedS Adenosyl Methionine is the methyl donorStep III Creatine KinaseThird step in the MuscleCreatine Phosphate is formedStep IVOccur spontaneouslyCreatinine is formed.