• Unambiguous: Each codon specifies only 1 amino acid.
• Degenerate/redundant: Most amino acids are coded by multiple codons.
  • Wobble—codons that differ in 3rd, “wobble” position may code for the same tRNA/amino acid. Specific base pairing is usually required only in the first 2 nucleotide positions of mRNA codon.
  • Exceptions: methionine (AUG) and tryptophan (UGG) encoded by only 1 codon.
• Commaless, nonoverlapping: Read from a fixed starting point as a continuous sequence of bases.
  • Exceptions: some viruses.
• Universal Genetic code is conserved throughout evolution.
  • Exception in humans: mitochondria.