This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Taurine seen in bile acid metabolism is synthesized from which amino acid ? 
Select and explain. 
A. Serine, B. Cysteine, C. Methionine, D. Glycine
B: Cysteine
Answer: B: Cysteine 
Explanation: Ans. is 'b' i.e., Cysteine Taurine is synthesized from cysteine. Synthesis of other impoant amino acid is as follows :? Glutamate is synthesized from a-ketoglutarate by enzyme glutamate dehydrogenase. Glutamine is synthesized from glutamate by enzyme glutamine synthase. Alanine is synthesized from pyruvate by transamination. Aspaate is synthesized from oxaloacetate by transamination. Asparagine is synthesized from aspaate by enzyme asparagine synthase. Serine is synthesized from 3-phosphoglycerate (a glycolytic intermediate). It can also be synthesized from glycine as conversion of serine to glycine is reversible. Glycine is synthesized from (i) glyoxylate and glutamate or alanine; (ii) choline; and (iii) serine Proline is synthesized from glutamate Cysteine is synthesized from methionine and serine Tyrosine is synthesized from phenylalanine.