Summary:
- A protein is an organic compound made up of small molecules called amino acids.
- There are 20 different amino acids commonly found in the proteins of living organisms.
- A protein may have up to four levels of structure.
- The order of amino acids, together with the properties of the amino acid, determines the shape of the protein.
- The structure of a protein starts with its sequence of amino acid.
- The complex structures of different proteins give them unique properties.
- Proteins play many important roles in living things.