Proteins are large biochemical complexes that contain several polypeptide compounds (amino acid chains). They are organized into four levels of structure.
The chain of amino acids that make up the protein; this chain directly controls the other levels of protein structure.
The patterns formed by segments of the polypeptide chain; can be either α-helices or β-pleated sheets.
The folding of the polypeptide to produce a certain shape.
The geometrical bonding of several polypeptides to form the protein.