2.3 - C - Lipids
Lipids are a class of carbon compounds that share the property of being insoluble in water. Each is a polymer that is made up of monomer fatty acids. In general, lipids are better In general, fatty acids can be classified as: saturated, monounsaturated or polyunsaturated:
Fatty Acids (U2)
Fatty acids with only single bonds between each carbon. Therefore, the molecule contains as many H atoms as possible. Fatty acids that have one or more double bonds are unsaturated.
Fatty acids that contain ONE double bond between carbon atoms.
Fatty acids that contain more two or more double bonds between carbon atoms.
Unsaturated Fatty Acids (U3)
As stated above, unsaturated fatty acids occur when double bonds form between carbon atoms in the chain. These fatty acids can be further subdivided into two additional categories:
Triglycerides are one of the main groups of lipids. They are formed by the condensation reaction between one glycerol and three fatty acids, which results in three water molecules being produced. The bond between each fatty acid and the glycerol is a ester bond, which forms between acids (-COOH in this case) and -OH groups.
Triglycerides are used as energy stores, as the energy contained in the molecule can be released during aerobic respiration. They are useful as heat insulators because they do not conduct thermal energy well.
Energy Storage (A3)
Lipids that are used as fats are normally used for long term energy storage. They are stored in specialized groups of cells called adipose (fat) tissues. Reasons for this include:
Lipid Structure Overview