If you had a four-letter alphabet and all words were three letters, then how many words would there be? The answer is 4 times 4 times 4, or 4-cubed, or 4^3, or 64. That’s how the DNA code works. Our DNA has four molecular “letters” and to create a protein the letters are taken three at a time in words called “codons.” Each codon specifies an amino acid and these 64 different codons are mapped to 20 different amino acids (and a “stop” signal). Since the 64 different codons far exceeds the 20 different amino acids and the stop signal, the code is degenerate. In other words, there are multiple codons that map the same amino acid (just as “absurd” and “ludicrous” have similar meanings). Read more