Functions:
>Store twice as much energy per gram than carbohydrates.
>Energy storage in plant seeds.
>Form adipose tissue of animals.
>Protection of delicate internal organs.
>Produce metabolic water when oxidised.
Properties:
>Insoluble but dissolve in organic solvents, e.g.ethanol.
>Oils are liquid at room temperature while fats are solid.
Triglycerides:
General formula of glycerol- C3H8O3
Components of a fatty acid- Carboxyl group, hydrocarbon chain, and a methyl group.
They are formed by the condensation reaction between ONE glycerol molecule and THREE fatty acid molecules. A molecule of water is removed and an ester bond is formed. Remember that glycerol never loses the oxygen and the fatty acid always loses its OH group.
Phospholipids:
Similar to triglycerides but with one of the FA groups replaced by a phosphate group.
Waxes:
Similar to fats and oils but also contain alcohol.
They are insoluble and reduce water loss in plants as they make up the waxy cuticle. This stops the osmotic effect and effectively reduces transpiration.
There are two types of fatty acids; Saturated and Unsaturated.
Saturated-
>Carbon atoms are joined by single covalent bonds.
>Hydrocarbon chain has maximum number of hydrogen atoms bonded to carbon.
>Found in animals.
>Contribute to heart diseases because they are solid at physiological temperatures and can block vital blood vessles.
Unsaturated-
>Carbon atoms are joined by 1/1+ double bonds.
>Hydrocarbon chain has less than maximum number of hydrogen atoms bonded to carbon.
>Found in plants.
>Higher level of HDL (high-density lipoproteins) means harmful fats are disposed so there is a lower risk of heart disease.
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