Functions of Lipids

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The biological functions of the lipids are as diverse as their chemistry. Fats and oils are the principal stored forms of energy in many organisms. Phospholipids and sterols are major structural elements of biological membranes. Other lipids, although present in relatively small quantities, play crucial roles as enzyme cofactors, electron carriers, light-absorbing pigments, hydrophobic anchors for proteins, “chaperones” to help membrane proteins fold, emulsifying agents in the digestive tract, hormones, and intracellular messengers.

Some of the functions of lipids are as follows:

  1. The glycerophospholipids are the main structural component of biological membrane.
  2. Lipids regulate membrane permeability.
  3. Polyunsaturated phospholipids are important constituents of phospholipids, they provide fluidity and flexibility to the cell membranes.
  4. They help in insulation, both thermally (triglycerides) and electrically (sphingolipids).
  5. Lipoproteins that are complexes of lipids and proteins, occur in blood as plasma lipoprotein, they enable transport of lipids in aqueous environment, and their transport throughout the body.
  6. Triglycerides, stored in adipose tissue, are a major form of energy storage both in animals and plants.
  7. Soap was previously manufactured from animal fat. Now-a-days plant fats are used for this purpose.
  8. Essential fatty acids like linoleic and linolenic acids are precursors of many different types of ecosanoids including prostaglandins, thromboxanes. These play a important role in pain, fever, inflammation and blood clotting.
  9. Edible oils extracted from many seeds are used in cooking. Animal fats present in milk yield butter and ghee.
  10. They help in the protection of internal organs (e.g. triglycerides and waxes).
  11. They help in cell signaling.
  12. Fats can be converted to carbohydrates. Therefore, fats stored in oil seeds (e.g., Groundnut, Mustard, Castor, Sun­flower, Cotton, and Coconut) not only provide energy but also raw materials for growth of embryo.
  13. Lipids are components of some enzyme systems.
  14. Cholesterol maintains the fluidity of membranes by interacting with their complex lipid components.
  15. In birds, oil from preen gland is used to lubricate feathers and protect them from wetting. Hair are similarly lubricated in mammalian skin. It prevents their felting. The skin is also protected from drying up.
  16. The fat-soluble vitamins (A, D, E and K) are essential nutrients stored in the liver and fatty tissues.
  17. Acyl-carnitines are involved in the transport and metabolism of fatty acids in and out of mitochondria, where they undergo beta oxidation.
  18. Cholesterol is the precursor of bile acids, Vitamin D and steroids.
  19. Desert animals employ fat as source of metabolic water, e.g., Kangaroo Rat, Camel. Kangaroo or Desert Rat does not drink water. Camel uses fat stored in its hump for obtaining metabolic water during extreme desiccating conditions.
  20. On digestive tract, Lipids facilitate the digestive process depressing gastric secretion, slowing gastric emptying and stimulating biliary and pancreatic flow.
  21. They affect the texture and flavor of food and so its palatability. Food manufacturers use fat for its textural properties, e.g. in baked goods fat increase the tenderness of the product. Chefs know that fat addiction add to the palatability of meal and increase satiety after a meal.
  22. When skin temperatures drop too far, layers of fat beneath the skin metabolize to raise them.