Three levels of protein structure are primary, secondary and tertiary.

a. Describe the primary structure of a typical protein containing one polypeptide chain. Name the type of chemical bonding involved in the primary structure of a protein.

b. Describe how hydrogen bonding stabilises the α-helical secondary structure of a protein.

c. The tertiary structure of a protein is stabilised by interactions between the side-chains of particular amino acids. Describe four different types of interactions that maintain the tertiary structure of a protein. For each type of interaction give an explanation of how the attractive forces arise.