The necessity of a contingent code

But the use of a code implies that information is being transferred by a mechanism that is not determined by physics and chemistry. The code has rules and attaches meaning to otherwise arbitrary collections of symbols.

The code is written in the four letter alphabet of the bases and translated to the 20 letter alphabet of the amino acids.

To further illustrate what is meant by a contingent code, consider the magnetic letters fixed to the magnetic board at right. The letters are held to the board by the magnetic forces, but those forces do not impose any specific ordering of the letters. The letters can be arranged to spell out a meaningful message in the English language (code) or to form a meaningless sequence like the one at bottom.

DNA Environment Makes the Code Independent of the Chemistry

The DNA environment provides a contingent code of complementary bases with a read/write mechanism similar to a computer code system.

Meaning is given to combinations of symbols, like a language

Three-letter combinations from the four-letter alphabet of bases form the genetic code. These base triplets act as codons to specify one of the letters of the 20 letter alphabet of amino acids. With three letters out of four possible, there are 4³ = 64 possibilities. So the code is redundant, but in a purposeful way. The redundancy takes care of the majority of single-base errors in coding.