| About one-third of the protein in the average UK diet comes from plant sources and two thirds from animal sources. The World Health Organisation estimates we need 4.5% of our calories from protein.
Proteins consist of chains of hundreds or thousands of amino acids units. There are only about 20 different amino acids but
the way the sequences can be arranged is almost infinite. It is the specific and unique sequence that gives each protein its
characteristic structural and enzymatic properties. |