Describe the role of Lipids in Living Organisms

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Describe the role of Lipids in Living Organisms

          Lipids are ‘a large and varied group of organic compounds, (3) ‘which are insoluble in water, but soluble in organic solvents such as ethanol and ether.’ (7). The molecules contain atoms of hydrogen, carbon and oxygen.  ‘The ratio of hydrogen to oxygen atoms is always greater than 2:1.’ (2)

          ‘Triglycerides are fats and oils and are made when glycerol form condensation reactions with three fatty acids to produce ester bonds.’          (2). At 20ºC fats are solids whereas oils are liquids.  One of the major roles of lipids in organisms is the use of these fats as energy stores.  ‘Upon breakdown they yield 38 kJ/g of energy compared favourably with carbohydrates which yield 17 kJ/g,’ (3) so they therefore store twice as much energy than carbohydrates.  Animals store fat when hibernating and ‘fat is also found below the dermis of the skin of vertebrates where it serves as an insulator.’ (10). Plants usually store oils and a small mass for energy is used ‘in plants where the dispersal of small seeds by wind or insects is much easier.’ (9).  Triglycerides are also  ‘compact, insoluble, can be stored at high concentrations, without requiring water as a solvent and are not mobilised as easily as carbohydrates,’ (5) which makes them ‘long term energy stores.’ (5)

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          Fats also act as ‘shock absorbing layers.’ (2). This protects delicate organs such as the kidneys or the heart from physical damage.  Aquatic mammals such as whales have ‘extremely thick subcutaneous fat, called blubber.’ (3). The blubber is extremely important in thermoregulation as underwater ‘hair is ineffective as an insulation because it cannot trap water in the same way as it can air.’ (10). Therefore as it is a poor conductor of heat, the layer of fat under the skin of aquatic mammals helps them to keep warm in cold climates.  Fats aid buoyancy in ...

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