Nucleic acids, such as deoxyribonucleic acid and ribonucleic acid, are composed of a sequence of three nucleotides called codons. These units correspond to one of the 20 amino acids used to build proteins. Codons are classified into two types: RNA and DNA.
RNA codons, which are involved in genetic translation, are formed in one type of RNA called messenger RNA, or mRNA. Aside from the mRNA codon ACA, the amino acid threonine is also encoded by the ACC, ACU and ACG codons.Learn more about Acids & Bases