This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Classification and metabolism of amino acids, Subject name: Biochemistry
Nontoxic form of storage and transpoation of ammonia: 
Select and explain. 
A. Aspaic acid, B. Glutamate, C. Glutamine, D. Glutamic acid
C: Glutamine
Answer: C: Glutamine 
Explanation: Catabolism of amino acid give rise to ammonia which get transferred to glutamate. From glutamate, NH3 is ultimately taken up by glutamine which is Non-toxic form of storage and transpoation of ammonia in blood (see fig below). Glutamine is neutral in nature and can readily move across cell membrane by facilitative diffusion. Glutamine is formed from glutamate by following reaction: