Codons are present in
A triplet sequence of nucleotides on the mRNA is the coson for each amino acid. The codons are on the mRNA. Each codon is a consecutive sequence of three bases on the mRNA , Eg : UUU codes for phenylalanine. Reference : DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION ; PAGE NO : 598
t-RNA
r-RNA
m-RNA
si-RNA
Metabolism of nucleic acids