What are lipoproteins and what is their function?

Lipoproteins are proteins that transport hydrophobic lipids in water based (polar) solutions such as blood. The two main types you need to know about for the IB biology course as part of option D includes HDL and LDL. LDL transports cholesterol from the liver to body cells for use, whilst HDL transports cholesterol from the body cells to the liver for storage. Fats in the diet can influence level of HDL and LDL production in the body, and hence blood cholesterol levels.