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Disaccharides

Disaccharides. Disaccharides. 3 main disaccharides-sucrose maltose lactose All are isomers with molecular formula C 12 H 22 O 11 . On hydrolysis they yield 2 monosaccharide. Soluble in water

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Disaccharides

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  1. Disaccharides

  2. Disaccharides • 3 main disaccharides-sucrose maltose lactose • All are isomers with molecular formula C12H22O11. • On hydrolysis they yield 2 monosaccharide. • Soluble in water • Even though they are soluble in water, they are too large to pass through the cell membrane.

  3. Structure of Disaccharides. • Formed by combination of 2 monosaccharides. • Bonds between 2 monosaccharide are known as Glycosidic bond. • Consider a combination of a molecule of alpha –glucose and a molecule of beta glucose, the product is a beta maltose and water.

  4. Formation of maltose

  5. Glycosidic linkage between glucose.

  6. Fermentation • Sucrose and maltose will ferment when yeast is added because yeast contains the enzyme sucrase and maltase. • Lactose will not ferment because yeast does not contain lactase.

  7. Testing for disaccharides • The chemical reactions of these sugars can be used to distinguish them in the laboratory. • If you have 2 test tubes containing a disaccharide,C12H22O11.To determine if it is sucrose lactose or maltose. • We can use the alkaline Cu complex reaction of glucose and the principle of fermentation.

  8. Sucrose • Is a sugar used at home • Also known as the cane sugar • When hydrolyzed, it forms a mixture of glucose and fructose.

  9. Maltose • Commonly known as malt sugar. • Present in germinating grain • Produced commercially by hydrolysis of starch.

  10. Lactose • Commercially known as milk sugar. • Of animal origin • Bacteria cause fermentation of lactose forming lactic acid. • When these reaction occur ,it changes the taste to a sour one.

  11. Formation of sucrose.

  12. Polysaccharides • Are polymers of monosaccharides. • Hydrolysis produces many molecules of monosaccharide. • Can be formed from pentoses or the 5 carbon sugars or the hexoses or six carbon sugars. • Those from pentoses are called pentosans • Those from hexoses are hexosans or sometimes called the glucosans. • The hexosans are most common in terms of physiology. • The hexosans have the general formula (C6H10O5)x

  13. Polysaccharides • The hexosans have the general formula (C6H10O5)x. • Where x is a large number. • Some of the common hexosans are starch, cellulose and dextrin.

  14. Starch • Insoluble in water • Gives a characteristic blue colour with iodine. • Test is used to determine the presence of starch in any solution or even to test for iodine.

  15. Cellulose • Wood, cotton and paper are composed primarily of cellulose.

  16. Glycogen • Is present in the body and stored in the liver and muscles. • Where it supplies glucose. • Forms a colloidal solution in water and gives a red color with iodine. • Glycogen is formed in the body cells from molecules of glucose. In a process called glycogenesis. • When glycogen is hydrolyzed to glucose, the process is called glycogenolysis.

  17. Heparin • Is a polysaccharide used as blood anticoagulant. • It accelerates the inactivation of thrombin and other blood-clotting agents • It’s the strongest organic acid found in the body • Other polysaccharides are Dextran and Heparin.

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