The Building Blocks of DNA

The long ribbon like molecule of DNA is composed of four sub units known as bases.

These are

The letters are used as shorthand to represent the coding sequences uncovered.

Groups of three "bases" are used to code for an amino acid. Within the active section of DNA group of three bases is known as a codon. There a maximum of sixty four possible codons, but in fact only twenty amino acids are used in the construction of proteins. Some amino acids are coded for by more than one codon, and there are also codons that code for stop.