The Biological Importance of Lipids
Lipids are organic compounds found in all types of plant and animal cells. They always contain carbon, hydrogen and oxygen, however the relative amount of oxygen is less than the amount of carbohydrates in lipids. Lipids are polymers and the long chains of repeating units are joined together in a condensation reaction where water is also produced. The most common types of lipids are triglycerides, phospholipids and waxes. Triglycerides are formed by three fatty acids and glycerol linked together by an ester bond. The three fatty acids that make up the triglyceride bond may be identical but a mixture of fatty acids is possible therefore many different triglycerides structures can be formed and this means that they have a range of functions (1). Saturated fats contain single bonds between carbon atoms and they are usually solid at room temperature. Unsaturated fats such as vegetable oils are liquid at room temperature and have many double bonds between carbon atoms.
Lipids form excellent energy storage molecules for example as fats in seeds, lipid deposits in the stroma of the chloroplast and adipose tissue of vertebrates. In addition oxidation of lipids yields more ATP than the oxidation of carbohydrates and therefore they are high-energy molecules, which are important for fruits or seeds to be dispersed. This is because just as the oxidation of glucose, acetylcoenzyme A is produced in the first stage, but so are many molecules of NAD and FAD. In lipids these are reoxidised in the electron transport chain and that’s why they provide more than twice the energy as the same mass of carbohydrate. Also saturated fats contain more energy that unsaturated fats there are more Hydrogen’s, therefore more to reduce the NAD/FAD during the respiration process (1). There is no osmotic effect in lipids so they cannot diffuse away and this helps them to be am excellent storage molecule. Furthermore another major biological function of...
Please join StudyMode to read the full document