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COURSE BIOMOLECULES Lesson Functions and importance of Lipids Dr. Praveen Kumar Agrawal
Functions of lipids Components of food Fats are the important components of the food. They form high calorie energetic food, in the form of butter, milk cream, oil and ghee. Oils are also present in vegetables. * Reserve food Fats also acts as a reserve food in animals and plants both. Hibernating animals, camel and migratory birds all store extra quantity of fats. Plants store their food in fruits and seed. Seeds of coconut, castor, mustard, and sunflower are all very rich in stored fat. e Energy provider Fats are the richest source of energy. Their calorific value (9.45 kcal) is more than that of carbohydrates (4.1 kcal). Oxidation of fats produces 2 times the energy yielded by the same amount of glycogen. (However carbohydrates are much quicker in providing energy) * Thermal insulator Fats in animals gets deposited in droplet form in adipocytes. These adipocytes cell and adipose tissues form a thick and insulating layer below the skin. This layer provides protection against cold. In whales, there is very thick layer of subcutaneous fat, called blubber. Structural componentLipids in the form of phospholipids form the main structural framework of biomembranes (plasma membranes, thylakoid membrane etc.). Precursors of vitamins and hormones: Lipids are the main prerequisite of many vitamins such as A, D, E and K. Steroid lipids such as cholesterol, is the main prerequisite of many hormones like progesterone, estrogen and testosterone. Shock absorber : In animals, fatty layers and deposits form shock absorbing cushions around eye ball, kidneys, testes and ovaries etc. *
Commercially important : Plant oils are hydrogenated to produce vegetable ghee which commercially very important. Oils are used to manufacture soap, detergents etc. Others Steroid Diosgenin (obtained from Dioscorea or Yam) is used to prepare anti-fertility pills. Desert animals use stored fat as a source of water. (Camel, rats, kangaroo etc.) Myelin sheath of some nerves helps to increase the rate of impulse transmission. Prostaglandins (local hormones), present in semen, are 20 carbon lipid derivatives. Cholesterol is important in forming the bile salts (bilirubin and biliverdin). Cutin or cuticle on epidermis of plant cells help to reduce transpiration rate. e Suberin provides strength and flexibility to cork cells. Oily secretions from the body help to nourish and lubricate outer surfaces. Waxy coating on leaves also reduces transpiration. Ear wax also lubricates ear drum.
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