Alanine, Miller-Urey experiments

X can be any of the four nucleobases—G, A, C or U thus, four anticodons can be formed GGC, GAC, GCC and GUC. The antiparallel structure contains the codons GCC, GUC, GGC and GAC. Today, these codons code for the four amino acids alanine, glycine, valine and aspartic acid. These are, astonishingly, the four protein building blocks produced in the best yields in the Miller-Urey experiment, and they... 

Finding the fragments. Identify the likely source (CH4, NH3, H2O, or H2) of each atom in alanine generated in the Miller-Urey experiment. 

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