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Year 9 iGCSE - Biology

Observe the picture above. The first thing you’ll notice how much larger, a lipid molecule is, compared to a carbohydrate molecule.

A Lipid is a large molecule made from smaller units of fatty acids and glycerol.

In the diagram to the right, you can see how three long chains of carbon atoms are attached to a glycerol molecule, with its three carbon atoms.

Together they combine to make one lipid molecule.

Lipids and carbohydrates are the bodies energy storage molecules. Carbohydrates are used for quick energy, where as fats are used slow energy releases.

On a weight basis, fat stores twice as much energy as the same weight of polysaccharides.

The Crucible on the left has 20 grams of sugar, while the  Crucible on the right has only 10 grams of vegtable oil.

Notice how much longer it takes for the oil to completley burn out compared to the sugar.

   Phospholipids have:

Another common lipid is a Phospholipid. It is the main component of all membranes within the cell.