The Genetic Code

The universal genetic code is the logical mapping that specifies how genetic information stored in DNA and mRNA determines protein sequence. It was discovered by Watson and Crick and since then was found to be common to all living organisms, with only minor and rare differences. Each triplet of bases is called a codon, and codes for a specific amino acid. There are also special codons, called stop codons , which are used to signal the termination of the protein synthesis process. Since there are 64 possible codons (minus three stop codons), and only 20 amino acids, different codons may be used to code for the same amino acid.

  

Figure: the genetic code