LIPIDS As

Introduction Lipids are fats and oils, which are important sources of energy in the diet . They have other uses as well. Energy is stored in the body as fat. As well as being an important energy store, the fat stored under the skin of mammals is an important insulation layer which helps to keep the body warm. Lipids are also important in the structure of cell membranes.

Forming lipids from glycerol and fatty acids Lipids are made from glycerol and fatty acids bonding by a condensation reaction this reaction is reversible via hydrolysis. H H O H - C- OH O Condensation H - C - O - C - R^ H - C- OH + C - R* H - C - OH + H2O H - C- OH OH Hydrolysis H - C - OH H H * R group made up of a hydrocarbon chain ^ can be more saturated

Saturated or Unsaturated Carbon atoms can bond with other carbon atoms to form a carbon-carbon bond.There are lots of these bonds in fatty acid molecules. Sometimes there is a double bond between 2 carbon atoms in a fatty acid. If all of the carbon-carbon bonds in he R group are single bonds , the fatty acid is said to be SATURATED. However if some of the carbon-carbon bonds are double bonds, the fatty acid is said to be UNSATURATED. See next page for pics.

This shows the structural differences between a saturated fatty acid (top), monounsaturated fatty acid (middle), and polyunsaturated fatty acid (bottom).

Triglycerides Triglycerides that contain long, Saturated Fats tend to form hard fats like lard + butter, which are solid at room temperature. Triglycerides that contain shorter unsaturated fatty acids are called Unsaturated Fats. They rend to form oils which are liquid at room temperature like sunflower oil or olive oil.

Phospholipids Phospholipids are a special type of lipid ; They have 2 fatty acid chains These form a tail which is Hydrophobic ( water hating ) The phosphate group is Hydrophillic ( water loving )