Lipids

Lipids

Lipids are fats, oils and waxes, organic compounds containing carbon,

hydrogen and oxygen. The same three elements are involved in the

structure of carbohydrates, but the amount of oxygen in the molecule

present is much less than in carbohydrates. Lipids are insoluble in

water but soluble in organic solvents such as acetone and ether. They

are relatively small molecules compared to the polysaccharides, but

because they are insoluble they tend to join together to form

globules.

Lipids can be split into the following

They are glycerol, fatty acids, oils, fats, waxes, phospholipids and

triglycerides (ester).

The properties of the fats are,

· Fats are insoluble in water but soluble in organic solvents.

· Behave as water hating molecules ( hydrophobic molecules)

· They are relatively small in size.

· Fats are solids at room temperature

Oils

· Insoluble in water but soluble in organic solvents

· They are relatively small in size

· Behave as water hating molecules ( hydrophobic molecules)

· Oils are liquids at room temperature

Wax

· Insoluble in water but soluble in organic solvents

· Behave as water hating molecules ( hydrophobic molecules)

· They are relatively large molecules

· Wax is a solid at room temperature.

Naturally occurring fats, oils and wax are esters formed by

condensation reaction between glycerol (an alcohol) and organic acids

known as fatty acids (Stearic acid) with the expulsion of 3 water

molecules.

Alcohol + Organic Acid à Ester + Water

(Glycerol) (Fatty acid) (Triglyceride)

Glycerol has the formula of C3H8O3. All of the three hydroxyl ...

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... long chain alcohols. In the living

world wax is used as waterproofing for plants and animals, honey bees

produce wax to make honey combs and the cells in which the eggs are to

be laid and where the development of larvae takes place.

The following are the uses of lipids in the living world

* Food stores in seeds ---lipids are stored as food in seeds of

plants i.e. sunflower

* Insulation ---the adipose layer--- lipids insulate the body of

animals (humans) from very cold weather.

* Protect vital organs--- lipids tend to cover the vital organs of

animals i.e. if there was an accident the vital organs will be

saved (kidneys, heart)

* Buoyancy in aquatic animals---lipids help aquatic animals (mammals

i.e. see lions, whales, penguins and all kind of fishes) to float

on water.