八、遗传密码
密码子的第二位
| 密码子的第一位（5’端） | | U | C | A | G | | 密码子的第三位（3端’） |
| U | UUU | Phe | UCU | Ser | UAU | Tyr | UGU | Gys | U |
| UUC | Phe | UCC | Ser | UAC | Tyr | UGG | Gys | C |
| UUA | Leu | UCA | Ser | UAA | 终止（赭石） | UGA | 终止（乳白） | A |
| UUG | Leu | UGG | Ser | UAG | 终止（琥珀） | UGG | Trp | G |
| C | CUU | Leu | CCU | Pro | CAU | His | CGA | Arg | U |
| CUC | Leu | CCC | Pro | CAC | His | CGC | Arg | C |
| CUA | Leu | CCA | Pro | CAA | Gln | CGA | Arg | A |
| CUG | Leu | CCG | Pro | CAG | Gln | CGC | Arg | G |
| A | AUU | Ile | ACU | Thr | AAU | Asn | AGU | Ser | U |
| AUC | Ile | ACC | Thr | AAC | Asn | AGC | Ser | C |
| AUA | Ile | ACA | Thr | AAA | Lys | AGA | Arg | A |
| AUG | Met | ACG | Thr | AAG | Lys | AGC | Arg | G |
| G | GUU | Val | GCU | Ala | GAU | Asp | GGU | Gly | U |
| GUC | Val | GCC | Ala | GAC | Asp | GGC | Gly | C |
| GUA | Val | GCA | Ala | GAA | Glu | GGA | Gly | A |
| GUG | Val | GCG | Ala | GAG | Glu | GGG | Gly | G |
