Proteins

Proteins are polymer structures made from different amino acids. The number of amino acids within a sequence can vary from 20 amino acids to thousands of amino acids long.

There are 4 different structures that proteins can have:

1.Primary Structure - linear amino acid sequence
2.Secondary Structure - gives rise to an alpha helix or beta pleated sheet held together by hydrogen bonds.[1]
3.Tertiary Structure - gives rise to a single peptide 3D structure held together by various bonds such as hydrogen bonding, disulphide bonding, salt bridges and non-polar hydrophobic interactions.
4.Quaternary Structure - describes multiple peptide chains
 that interact through various types of bonding to form a fully functional protein e.g. haemoglobin.

[1] Elliott.W.H, Elliott.D.C (1997) Biochemistry and Molecular Biology. New York, United States:Oxford University Press.pp.47-49.ISBN 0199271992