A series of paired nucleotides at a particular location on a chromosome (this location is called a locus). These paired nucleotides contain the basic blueprint for a particular protein, which is then used by the body.

How a gene becomes a protein:

Messanger RNA attaches to the unwound DNA strand, reads it, and alters the code slightly. Then transfer RNA binds onto the mRNA. Transfer RNA is composed of a cluster of three nucleotides on one end which attaches to and reads the mRNA, and a specific amino acid on the other end. As the transfer RNA binds onto the RNA strand, the amino acids on the other end line up to form a protein.