The Universal Genetic Code & Wobble Decoding

mRNA Codon (5′→3′)

Decoded

Codon AUG → Met (M)

Synonymous codons

GC content

33%

Wobble anticodon bases that can read position 3

U, I (2)

Nonpolar Polar Basic Acidic Stop

How it works

Every one of the ~19,700+ life forms this catalogue models shares the same dictionary: a 64-entry table mapping each 3-base mRNA codon to one of 20 amino acids (or a stop signal). This is the "universal genetic code" — nearly identical from bacteria to humans, strong evidence the whole tree of life descends from one common ancestor (LUCA).

64 codons (4³) → 20 amino acids + 3 stop codons
Reading frame: mRNA is read 5'→3' in non-overlapping triplets
Redundancy: most amino acids have 2-6 synonymous codons

The code is degenerate but not ambiguous: a codon always specifies exactly one amino acid, but most amino acids are specified by several codons that usually differ only at the 3rd ("wobble") position — Leucine, Serine and Arginine each have 6.

The wobble hypothesis (Crick, 1966) explains why: the tRNA anticodon's first base (position 34, pairing with the codon's 3rd base) tolerates non-Watson-Crick pairing, so one tRNA can decode several synonymous codons:

Anticodon wobble base → codon 3rd base it can read
  G  → C or U
  U  → A or G
  I (inosine) → U, C, or A
  C  → G only
  A  → U only

Base buttons — set the 1st, 2nd and 3rd base of the mRNA codon; the matching node lights up on the 3D codon wheel (ring = 1st base, sector = 2nd base, leaf = 3rd base).
Highlight synonymous codons — pulses every codon in the wheel that encodes the same amino acid as the current selection, showing the redundancy at a glance.
Random codon — jumps to one of the 64 codons at random.

Real-world relevance: this exact table is what a ribosome reads during translation, what mitochondrial DNA sequencing pipelines decode, and what codon-optimization tools rebalance when engineering a gene for expression in a different organism.

Selected codon Synonymous (highlighted)

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