PROTEINS STRUCTURE - AQA Biology A-Level/AS

sequence of amino acids in a polypeptide chain

hydrogen bonds between amino acids cause chain to coil to form a 3D shape called a alpha helix or a beta pleated sheet.

alpha helix is coiled further often to give a more specific 3D shape. 

May contain:

Disulphide bridges - strong covalent bonds so hard to break

Ionic bonds - between amino group and carboxyl group - weaker than disulfide bridges and easily broken by pH changes.

Hydrogen Bonds - numerous but easily broken

many polypetide chains linked together in various ways.

Can be prosthetic - non protein