The genetic code was deciphered by Har Gobind Khorana. All organisms have the same genetic code supporting that they share a common evolutionary history.
The genetic code is unambiguous, specific, degenerate & universal. Each codon codes for just one amino acid (or start or stop) The genetic code is redundant. Most amino acids are encoded by more than one codon. The Genetic code is a triplet and is read in mRNA in a contiguous fashion. Of the 64 codons, 61 code for amino acids, 3 code for nothing, thus act as stop codons. ( UAA, UAG, UGA) . AUG has dual functions – codes for methionine and also acts as a start codon.