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Lipids

What are they?
1. A group of substances that share the following characteristics
  1. Contain carbon, hyrdrogen and oxygen
  2. Proportion of O to C is smaller than in carbohydrates
  3. They are insoluable in water
  4. Soluable in organic solvents such as alcohhol and acetone
Roles of lipids
1. Main role in plasma membranes
2. As an energy source
  1. When oxidised, lipids provide more than twice the energy as the same mass of carbohydrates
3. Waterproofing
  1. Insoluable in water
4. Insulation
  1. Fats are slow conductors of heat and when stored beneath the body surface help to retain body heat
5. Protection
  1. Fat stored around delicate organs
Phospholipids
1. Similar to lipids except one fatty acid molecule is replaced by phosphate
2. Fatty acid molecules are hydrophobic
3. Phosphate molecules are hydrophillic
4. Hyrophilic head
  1. Interacts with water
5. Hydrophobic tail
  1. Mixes readily with fat, but orientates itself away from water
6. Said to be polar
Triglycerides
1. Made of 3 fatty acids and glycerol
2. No double bonds - saturated
3. One double bond - unsaturated
4. More than one double bond - polyunsaturated

Lipids

	Created by Beth Ritchie almost 11 years ago