Science Gateway > Resources > Biology Hypertextbook Index

3 Proteins

3 Proteins

Proteins are very complicated moleucules. With 20 different amino acids that can be arranged in any order to make a polypeptide of up to thousands of amino acids long, their potential for variety is extraordinary. This variety allows proteins to function as exquisitely specific enzymes that compose a cell's metabolism. An E. coli bacterium , one of the most simple biological organisms, has over a 1000 different proteins working at various times to catalyze the necessary reactions to sustain life.


3.1 Amino Acids Diagram

All amino acids have the same general formula:


The twenty amino acids found in biological systems are:


All proteins are linear chains composed of these 20 amino acids.


Check out the Amino Acid Repository, maintained by the Image Library of Biological Macromolecules, for an excellent summary of amino acid properties and great graphic images of the twenty amino acids.
Next Page Previous Page Directory Home
hyperbio@mit.edu