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LIPIDS
- soluble in non-polar organic solvents
- insoluble in water
- fats (solid at 20oC)
- oils (liquid at 20oC)
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- Triglycerides are non-polar and are thus relatively insoluble in water.
- Have lower density than water
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FUNCTIONS OF LIPIDS
- Energy store as they occupy less volume per unit mass than carbohydrates. Fats yield more energy due to chemical energy in C-C & C-H bonds. Energy released by oxidation of fatty acid chains
- compact & insoluble in water
- Easily hydrolysed into fatty acids and glycerol
- Oxidised to give metabolic water
- Thermal insulation
- Buoyancy in marine mammals
- Protection against mechanical damage
- Reduction of water loss
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STRUCTURE IN RELATION TO FUNCTION OF PHOSPHOLIPIDS
- 1 glycerol, 2 fatty acid chains, 1 phosphoric acid group
- Formation of cell membrance
- Formation of layer around neurons
- Regulates type of molecules entering/leaving the cell, as hydrophobic tail allows only lipid-soluble/non-polar molecules through
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- steroid found in cell membranes, transported in blood plasma
- amphipathic molecule
- Regulates fluidity of cell membranes
- Formation of bile salts
- Precursor molecule for synthesis of vitamin D, sex hormones and hormones of adrenal cortex
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