They serve two major functions in the cell.
Some proteins are enzymes that catalyze most biological reactions in a living organism.
Other proteins perform a structural role for the cell - either in the cell wall, the cell membrane or in the cytoplasm. In this section, we will look at the basic structure that all proteins have in common. Primary Stucture Protiens are polymers of amino acids. The side group gives each amino acid its distinctive properties and helps to dictate the folding of the protein. Figure 1 - A general amino acid.