Properties of the genetic code
There are several unifying properties of the genetic code.
The code is degenerate: several different codons correspond to the same amino acid.
The sequences GCC and GCA both code for alanine. Leucine is coded for by six different codons.
The combinations of bases that make up the codons are non-random. Codons that code for the same amino acid usually differ by just a single base.
The code is degenerate, or redundant, but it is never ambiguous. One codon can never specify two amino acids.
The code is universal. Apart from a few exceptions, the codons for amino acids are the same in all organisms.
The code is non-overlapping and continuous. The codons are read in discrete groups of three, as shown in the diagram below.
UAGUUCGGAAAG is read UAG UUC GGA AAG, not UAG AGU GUU UUC etc.