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Chemistry - Disaccharides

Disaccharides

Disaccharides contain two monosaccharide units. When two monosaccharide
units react together to form a disaccharide, a water molecule is released
in a condensation reaction. [1] For example, the disaccharide maltose may
be produced from reaction between two glucose molecules:

The reaction between adjacent monosaccharide molecules occurs at hydroxy,
-0H, groups and produces an ether, (C) - 0 - (C), link in which the oxygen
atom is covalently bonded to two carbon atoms.

The condensation nature of this reaction is emphasised in the equation:

The same molecular equation can also be applied to the formation of the
disaccharide, sucrose.

Maltose occurs in germinating grain and is formed during the hydrolysis
[2] of starch.

Sucrose, also known as table sugar or cane sugar, is present in many
fruits.

The third major disaccharide, is present in the milk of mammals - e.g.
six - eight per cent in human milk and four - five per cent in cow's milk.
It is produced in the mammary glands from glucose.

Many people suffer from lactose intolerance because they lack the enzyme
lactase necessary to digest lactose.

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[2] http://alison.com/#