Second position U C A UUU UCU UGU Phe UCC SSer UAc/yr Cys UGC UA UCA AA Stop UGA Stop A >Leu UUG UCG UAG Stop UGG Trp G CA CGU CUC CAC CGC Pro Arg CUA CCA CAA CGA GIn CUG CCG CAG CGG AUU ACU AAU AGU 巨| AUC>lle|ACC C AAl AGC Thr AUA ACA AAA Arg AUG Met ACG AAG AGG G GUU GCU GAU GGU As G GCC GAC GGC G Ala GUA GCA GAA GGA Glu GUG GAG GGG 减少了变异对生物的影响减少了变异对生物的影响