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Bodies main energy source CH 2 O Only plants synthesise carbohydrates Starch, Cellulose (polysaccharides) Lactose, sucrose (dissaccharides) Glucose, fructose.

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Presentation on theme: "Bodies main energy source CH 2 O Only plants synthesise carbohydrates Starch, Cellulose (polysaccharides) Lactose, sucrose (dissaccharides) Glucose, fructose."— Presentation transcript:

1 Bodies main energy source CH 2 O Only plants synthesise carbohydrates Starch, Cellulose (polysaccharides) Lactose, sucrose (dissaccharides) Glucose, fructose (monosaccharides) CARBOHYDRATES

2 (CH 2 O) n where n=3 to 9 Aldehydes or ketones containing a carbonyl group and at least 2 hydroxyl groups Hexoses (glucose, galactose, fructose) MONOSACCHARIDES

3 Contain 5 carbon atoms Ribose PENTOSES

4 Low molar masses Sweet Soluble in water Crystalline solids Reducing sugars (aldehyde group oxidised) PROPERTIES OF MONO AND DI-SACCHARIDES

5 STRUCTURE OF GLUCOSE

6 INTERCONVERSION OF Α AND Β GLUCOSE

7 STRAIGHT CHAIN AND CYCLIC FRUCTOSE

8 CONDENSATION OF MONOSACCHARIDES

9 DISACCHARIDE FORMATION Β-glucose + β-galactose -----> lactose α-glucose + α-glucose -------> maltose α-glucose + β-fructose ------> sucrose

10 Numerous monosaccharide units Large masses Not sweet, non-reducing, insoluble Starch is plant store for glucose Two forms : Amylose (water soluble) Amylopectin (water insoluble) POLYSACCHARIDES

11 α-1,4 glycosidic linkages AMYLOSE

12 α-1,4 glycosidic linkages as well as α-1,6 glycosidic linkages AMYLOPECTIN

13 More highly branched than amylopectin but also has α-1,4 glycosidic linkages as well as α-1,6 glycosidic linkages GLYCOGEN

14 Linear Made up of β-glucose units with all glycosidic linkages in the 1, 4-position Extensive hydrogen bonding between chains Strength, rigidity Insoluble CELLULOSE

15 MAJOR FUNCTIONS OF CARBOHYDRATES Energy Source Energy Reserve (e.g. glycogen) Precursor of other Biologically Important Molecules (e.g. anticoagulants, components of nucleic acids)

16 DIETARY FIBRE Plant material Cannot be digested by humans Parts of fruits, vegetables, grains May be digested by bacteria in gut Cellulose Lignin Pectin

17 IMPORTANCE OF HIGH FIBRE DIET Constipation and Diverticulosis Irritable bowel syndrome Obesity Crohn´s Disease Haemorrhoids

18 READING AND QUESTIONS Please read pages 331 to 334, all about carbohydrates. Take your own notes. Make a mind map. Can you answer the questions in the orange boxes (B.3.1 etc) ? Now answer questions 9 to 16 on page 359.


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