Most genes encode the instructions for producing a protein. In the cell, proteins called enzymes carry out most of the biochemical reactions that underlie life . Other proteins serve structural roles.
Genes have two main parts.
The protein coding sequence contains the structural blueprints for the protein . If the cell was a factory, the gene would be the master copy of a blueprint for a product. Each worker uses their copy of the instructions to make thousands of copies of the product. Equally important, the promoter controls when, where, and to what degree a gene is turned on . Like the volume control on a radio, the more highly expressed the gene is, the more copies of the mRNA are produced, hence the more copies of the protein product.