What are the differences between the different sturctures of proteins?

There are 4 different structural forms of proteins; Primary, Secondary, Tertiary and Quaternary. The primary structure is a chain of amino acids joined by peptide bonds. The secondary structure is a chain of amino acids that have been bent and folded into Beta pleated sheets and alpha helices. Between the Beta pleated sheets and Alpha helices, weak Hydrogen bonds form between electropositive and electronegative atoms. The tertiary structure, is the first form that has a 3-Dimensional structure. There are many different interactions and bonds that form at this level. Hydrogen bonds, hydrophobic interactions, di-sulphide bridges and ionic interactions. A protein showing the quaternary structure, is one that contains multiple tertiary structure proteins that also hold a prosthetic group to perform functions. An example of a prosthetic group would be the Fe2+ ions in a haemoglobin molecule.