<prompt> The following are stop codons EXCEPTUGAUAUUAAUAG  <response>: Ans. b UAU Ref. Harper, 27thChapter 37.; Chatterjee, 4th ed., 221PROTEIN SYNTHESIS:- Activation of Amino acids:-- Formation of aminoacyl tRNA by key enzyme-Aminoccyl tRNA synthatase-specific for a particular amino acid and also for tRNA- There are 20 different aminoacids one codon for one amino acid- Very high specificity is the most significant feature of this enzyme because once amino acid is attached to tRNA recognition of a specific codon on mRNA is due entirely to the tRNA not to the amino acid. Fidelity Faithfulness Initiation by Aug codon methionine Elongation Termination by terminator codons or stop codons or nonsense codon-UAA, UGA, UAGFidelity enzyme in protein synthesis-Aminoacyl tRNA sybnthetaseNull indicates no functional gene product 