DNA transcribed to RNA is then translated into proteins. The sequence of bases determines the amino acids to be added to the protein.
3 adjacent bases in the DNA strand codes for an amino acid. 3 adjacent bases are called codons. There are 64 possible codon combinations, but only 20 amino acids make up proteins.
One amino acid has more than one codon for it. During translation, depending on the sequence of bases, the codons, the amino acid to be added to the polypeptide chain is decided. For each codon the corresponding amino acid is added.
In this case there are 666 bases,
3 bases - code for one amino acid
therefore 66 bases - 66/3 = 22 amino acids are coded for by this portion of DNA
