The Structure and function oflipids

Lipids are non-polar compounds and therefore do not dissolve in polar solvents, but they do dissolve in non-polar solvents.

The triglycerides molecules are the biggest group of lipids and the energy store is found under the skin in adipose tissue, they consist of three fatty acid molecules joined by ester bonds (which are formed by condensation) to a glycerol molecule. They are the biggest group of lipids and the energy store is found under the skin in adipose tissue.  Fatty acids with double bonds in the hydrocarbon chain are unsaturated; others are saturated fatty acids.

The phospholipid molecules have two fatty acid molecules and a phosphate group joined to glycerol. The molecules are polar and have polar heads and form bilayers in aqueous systems. Lipids have many functions including insulation as they have subcutaneous fat, which is a good insulator, this is used by aquatic mammals, like the blubber on a seal.

Lipids are also energy stores and produce twice as much energy compared to carbohydrates and proteins. They also have a low mass, which is useful in animals, and seeds, which are dispersed by wind ect. Lipids also provide protection and is good packing tissue and protects delicate organs e.g. Kidneys. Another function is waterproofing, and mammals produce oil called sebum (produced by the sebaceous glands) Birds also produce it to waterproof their feathers. Lipids are also good for buoyancy, as they are less dense than water and so are good for aquatic vertebrates e.g. whales and fish, who store oil in their livers.