Your DNA contains
a set of instructions for building a human. These instructions are inscribed
in the structure of the DNA molecule through a genetic code. It works
Protein-coding DNA can be divided into
of three bases that specify an amino acid or signal the end of the protein.
Codons are identified by the bases that make them up in the example
at right, GCA, for guanine, cytosine, and adenine. The
cellular machinery uses these instructions to assemble a string of corresponding
amino acids (one amino acid for each three bases). The amino acid that corresponds
to "GCA" is called alanine; there are twenty different amino acids
synthesized this way in humans. "Stop" codons
signify the end of the newly built protein.
The completed protein is then released to do its job in the cell.