# Glossary

## Genetic code

The genetic code is the term applied to the encoding process by which RNA is translated into peptide chains of amino acids. Every RNA codon (triplet of nucleotides) becomes translated into precisely one amino acid, regardless of species.

Attempting to translate length 2 RNA substrings could only encode $4^2 = 16$ amino acids, yet 20 amino acids commonly appear in almost every species, which accounts for the need to translate codons.

The precise details of how the genetic code translates RNA codons into the 20-symbol alphabet for protein strings are shown in the figure below. Codons are formed by moving from the inside to the outside of the inner wheel, choosing one symbol in each spoke. For this information in table form, consult the RNA codon table (or the DNA codon table if we wish to view transcription and translation as a single step).