Final answer:
A protein's shape is determined by the sequence and interaction of amino acids. The primary structure determines the sequence of amino acids, which then fold to create the secondary, tertiary, and quaternary structures. Interactions between amino acid side chains help stabilize the protein's final three-dimensional shape, allowing it to function properly.
Step-by-step explanation:
The structure of a protein is determined by the sequence and interaction of amino acids. Proteins are made up of long chains of amino acids, known as polypeptides. The interaction between these amino acids, particularly the side chains, helps to fold the polypeptide into its final three-dimensional shape.
In the primary structure, the sequence of amino acids is determined by the genetic code. This sequence then determines how the polypeptide folds to create the secondary, tertiary, and quaternary structures.
In the secondary structure, the polypeptide chain forms either alpha helices or beta sheets. These structures are stabilized by hydrogen bonds between the amino acids.
In the tertiary structure, the polypeptide chain folds further and forms interactions such as hydrogen bonds, disulfide bonds, ionic bonds, and hydrophobic interactions. These interactions help to stabilize the overall three-dimensional shape of the protein.
In the quaternary structure, multiple polypeptides come together to form a functional protein complex.
An example of an amino acid side chain that can be found in the active site of an enzyme and form interactions is the amino acid histidine. Histidine has a side chain with a nitrogen atom that can act as a proton donor or acceptor, allowing it to participate in acid-base catalysis in the active site of an enzyme.