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
Glycine provides all in purine synthesis, except ? 
Select and explain. 
A. Carbon - 4, B. Carbon - 5, C. Nitrogen - 4, D. Nitrogen - 7
C: Nitrogen - 4
Answer: C: Nitrogen - 4 
Explanation: Ans. is 'c' i.e., Nitrogen - 4 In de novo synthesis, purine ring is formed from variety of precursors is assembled on ribose-5-phosphate. Precursors for de novo synthesis are ?Glycine provides C4, Cs and N7Aspaate provides NIGlutamine provides N3 and N9Tetrahydrofolate derivatives furnish C2 and CsCarbon dioxide provides C6