Importance of Proteins

Proteins are the functional units of living things and play a vital role in essentially all biological processes. Their major roles, as set out in this unit, are: (1) all the biochemical reactions that occur in living systems are catalysed by catalytic proteins called enzymes; (2) structural proteins such as keratin and collagen act as the structural backbone of tissues; (3) proteins are used to transport molecules (e.g. haemoglobin transporting oxygen) and organelles (e.g. the motor protein kinesin) within the cell, and to control the movement of molecules into and out of cells (transporter proteins); (4) antibodies, which are themselves proteins, help the body fight off various diseases; (5) proteins act as chemical messengers that coordinate many bodily functions -- insulin and glucagon, for example, together control the level of glucose in the blood; (6) proteins act as receptors that detect the presence of specific signal molecules an …