Genetic code

 The genetic code has four main features:

Three nucleotides/bases encode an amino acid, there are 20 different amino acids which are the building blocks for proteins.

The genetic code is non-overlapping, for example a sequence UGGAUCGAU is read UGG AUC GAU rather than UGG GGA GAU etc.

The code has no punctuation, so no base serves as a "comma" between groups of bases, therefore the code is read sequencially three bases at a time.

The code is degenerate, meaning more than one codon encodes for the same amino acid. There are 64 possible triplets yet only 20 amino acids so most amino acids are encoded by 2 or more codons. Triplets that code for the same amino acid are known as synonyms.

[Berg, Tymoczko and Stryer (2012) Biochemistry, 7th edition, New York: W. H. Freeman and Company]