(a) State four functions of proteins, giving a named example of each.

Proteins can function as 

1. Biological Catalysts: enzymes that decrease the activation energy of a reaction and facilitate the progression of chemical reactions

2. Hormones: proteins can function as hormones, normally produced by a gland. Hormones act as chemical messages by binding to a specific receptor and activate a particular cellular pathway. 

3. Channels/Pumps: proteins can comprise of strucrures located in the cell lipid bilayer. They allow for different types of molecules and compounds to exit or enter a cell. 

4. Structural proteins: These proteins are found in different tissues in our body but also comprise protein structures of prokaryotic/eukaryotic cells such as the flagellum, used for cell motility. Structural proteins can also be a part of human tissues, including keratin found on nails and hair cuticles.