Biochemistry - Lipids

Lipids make up around 5% of a living organism. Lipids has a variety of functions in the body:

• A source of energy: Lipids can be respired to generate ATP
• Energy storage: Lipids can be stored in adipose cells
• All membranes are made from lipids
• Insulation: Blubber in whales
• Protection: the surface of the plant cuticle is protected by a waxy layer
• Some steroid hormones (e.g. testosterone and oestrogen)

Fatty acids - these consist of a hydrocarbon chain with a carboxylic acid group on the end.

These can be found saturated and unsaturated; in plants the fatty acids tend to be unsaturated and result in them being in liquid form as a double bond changes the shape of the fatty acid so it is no longer straight chained. This means it cannot pack tightly thus resulting in the liquid form of the…