All carbohydrates are made up of units of sugar.Carbohydrates that contain only one sugar unit, eg glucose, or two sugar units, eg sucrose, are referred to as simple sugars.Complex carbohydrates, eg starch and cellulose, are long chains of simple sugar units bonded together.Lipids are molecules consisting of three molecules of fatty acids joined to a molecule of glycerol.Protein molecules are made up of long chains of amino acids. These long chains are folded to produce a specific shape that enables other molecules to fit into the protein. Proteins act as:
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