proteins

Amino acids are joined by peptide bonds to form polypeptide chains which are sequences of amino acids.

Polypeptides can be arranged in an alpha helix or beta pleated sheet. An alpha helix is a tight twisted strand where the polypeptides are tightly packed. In a beta pleated sheet the polypeptides are in zig-zag lines. Both contain hydrogen bonds between parts of the chain.

Quaternary structure is made up of more than one type of polypeptide and contains a prosthetic group which is a non-protein. An example is haemoglobin as it’s made up of multiple polypeptides.

Amino acids

The 3D structure of a protein that is specific to a proteins function