Describe the structure of proteins.

Proteins are macromolecules found within living organisms that have an array of crucial functions, including catalysing enzymatic reactions and providing structural stability to cells. At the basic level, all proteins are simply polymers of amino acids generated by the process of translation; amino acids are joined together at the ribosome via successive condensation reactions to generate peptide bonds. The primary structure of a protein is the order of these amino acids within the polypeptide and differs between different proteins. The primary structure can then determine the secondary structure, whereby hydrogen bonds enable the polypeptide to fold into alpha helices or pleated sheet structures. 3D or tertiary structure of a protein is formed due to a combination of hydrogen, ionic and disulphide bonds between the ‘R’ groups of the amino acids. The tertiary structure is the final, native structure for many proteins, however some proteins also have quarternary structure meaning that multiple polypeptide chains interact with each other to form the final functional structure.