Evidence suggests that the correspondence between DNA codons and amino acids (i.e. the genetic code ) is not random. A good place to start with this interesting topic is the Wikipedia article about the genetic code, in particular, about its origin:
Many hypotheses on the evolutionary origins of the genetic code have been proposed. Four themes run through the many hypotheses about the evolution of the genetic code:
Here I summarize the four themes (adapted from wikipedia).
Chemical principles governing specific RNA interaction with amino acids.
Biosynthetic expansion. The standard modern genetic code grew from a simpler earlier code through a process of "biosynthetic expansion".
Natural selection has led to codon assignments of the genetic code that minimize the effects of mutations.
Information channels: Information-theoretic approaches models suggest that the genetic code originated as a result of the interplay of the three conflicting evolutionary forces: the needs for diverse amino-acids, for error-tolerance and for minimal cost of resources.
Other models combine some of these hypothesis.
- The genetic code is one in a million. Freeland SJ, Hurst LD. J Mol Evol. 1998 Sep;47(3):238-48.
- Selection, history and chemistry: the three faces of the genetic code. Knight RD, Freeland SJ, Landweber LF. Trends Biochem Sci. 1999 Jun;24(6):241-7. Review.