Important Functions of Lipids (17 Functions)

The following points highlight the seventeen important functions of lipids.

(1) Fats serve as food reserve in both plants and animals. Hibernating animals store extra fat prior to onset of winter. Migratory birds also do so before migration.

(2) They function as concentrated food because as compared to carbohydrates they yield more than twice as much energy per unit weight (9.3 kcal/gm: 4.5 kcal/gm).

(3) 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.

(4) In seeds and spores lipids help in thermal insulation, protection from ultraviolet radiations and loss of water.

(5) Vitamin A, D, E and K are soluble in fats. The latter not only act as their carriers but also protect them from oxidation.

(6) In animals fat occurs as droplets inside cells called adipocytes. Adipocytes of cold blooded or poikilothermic animals have higher amount of unsaturated fatty acids as compared to warm blooded or homoeothermic animals.

Fatty or adipose tissue forms an insulating layer below the skin of animals for protection against low temperature. Whale has a very thick layer of subcutaneous fat called blubber. Animals of colder regions also have a thick fatty layer for insulation, e.g., Polar Bear.

(7) Subcutaneous fat rounds off the body contours of animals and human beings. In animals the fats produce a shock absorbing cushion around eye balls, gonads, kidneys and other vital organs.

(8) Edible oils extracted from many seeds are used in cooking. Animal fats present in milk yield butter and ghee.

(9) Plant oils are used as low cholesterol fat. They are also hydrogenated to form vegetable ghee.

(10) Soap was previously manufactured from animal fat. Now-a-days plant fats are used for this purpose.

(11) Drying oils having unsat­urated fatty acids are used in paint industry.

(12) Waxes form a protective layer over the animal fur. They protect the floating leaves of aquatic plants against wetting. In land plants they reduce the rate of transpiration.

(13) Myelin sheath around nerve fibres takes part in insulation.

(14) Phospholipids, glycolipids and sterols are components of cell membranes.

(15) Fragrance of many plant products is due to fat-like substances called terpenes.

(16) 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.

(17) 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.