Multiple choice Initiation codon for methionine is AAA UUU UAA AUG Reveal answer Fill a bubble to check yourself D Correct answer Explanation AUG is the universal start codon that codes for methionine and initiates protein synthesis in both prokaryotes and eukaryotes. UUU codes for phenylalanine, UAA is a stop codon, and AAA codes for lysine. The genetic code is nearly universal.