Which one of the<br/>following amino acids can be phosphorylated? () A: Tyrosine B: Alanine C: Aspartate D: Methionine E: Glutamine

Nitrogen or carbon atoms are contributed to the structure of the purine ring by amino acids, except: A: Glycine B: Glutamine C: Aspartate D: Glutamate

Which of the following is not the direct material of de novosynthesis of purine nucleotide ? () A: glycine B: aspartate C: glutamate D: CO2 E: one carbon unit