This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Amino Acids Basics, Subject name: Biochemistry
Gamma amino butyrate is synthesized from? - 
Select and explain. 
A. Fumarate, B. Glutamate, C. Histidine, D. Glycine
B: Glutamate
Answer: B: Glutamate 
Explanation: Ans. is 'b' i.e., Glutamate \Ref: Harper 29th/ e p. 304-305]o Gamma amino butyric acid (GABA) is formed by decarboxylation of L-glutamate.Amino acidsBiological important compoundTyrosineCatecholamines (epinephrineQ, norepinephrineQ, dopamineQ), thyroxineQ, triiodothryonine, melanin Q.(Note: - Phenylalanine is the precursor of tyrosine, thus it can also give rise to all these compounds through tyrosine (phenylalanine - TyrosineQ - CatecholaminesQ, thyroxineQ, T3, melaninQ).TryptophanVitamin niacinQ, melatoninQ, SerotoninQGlycineQ,ArginineQ,methionineQCreatineQGlycine, cysteineBile saltsGlycineHeme.Aspartic acid andglutaminePyrimidine basesGlycineQ, aspartic acid, glutaminePurine basesQb-alanineCoenzyme-AArginineNitric oxideQGlutamateGama-amino butyric acid (GABA)