DISACCHARIDES
- These contain two monosaccharide units
- The chemical process through which a large molecule (e.g a disaccharide) is formed from smaller molecules is called condensation and it involves loss of water
Common examples of disaccharides include sucrose, maltose and lactose
- Disaccharides are broken into their monosaccharide units by heating with dilute hydrochloric acid
- This is known as hydrolysis and involves addition of water molecules
- The same process takes place inside cells through enzymes
Sucrose + water = hydrolysis—————–glucose+fructose Properties of Disaccharides
- Sweet tasting
- Soluble in water
- Crystallisable
- Maltose and lactose are reducing sugars while sucrose is non-reducing sugar
- Sucrose is the form in which carbohydrate is transported in plants:
- This is because it is soluble andjchernically stable
- Sucrose is a storage carbohydrate in some plants e.g sugar-cane and sugar-beet
- Disaccharides are hydrolysed to produce monosaccharide units which are readily metabolised by cell to provide energy.
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