1. Proteins  Maintenance of structures  Proper functioning of all living organisms

2. Biological functions of proteins Enzymes- Catalyze biological processes e.g. Pepsin Hormones - Regulate body processes e.g. Insulin Storage proteins - Store nutrients e.g. Ferritin Transport proteins - Transport oxygen and other substances through the body e.g. Haemoglobin Structural proteins - Form an organism’s structure e.g. Collagen Protective proteins - Help fight infection e.g. Antibodies Contractile proteins - Form muscles e.g. Actin and myosin

3. Structure of Proteins The building units of proteins are called amino acids  All naturally occurring amino acids are  -amino acids

4. Most proteins are formed from some twenty common amino acids, linked up by peptide bonds Peptide linkage

5. Hydrolysis of proteins Separation of amino acids by paper chromatography Linked with 1. Phase equilibrium - Application of partition 2. Chemistry of amino acids

6. Carbohydrates As a source of energy Glycogen in animals, Starch in plants General formula C x H 2y O y Synthesized by photosynthesis 6CO 2 (g) + 6H 2 O(l) C 6 H 12 O 6 (s) + 6O 2 (g) light chlorophyll

7. Classification of Carbohydrates Monosaccharides - (CH 2 O) n where n>2 E.g. C 6 H 12 O 6 Hexose (most important) C 5 H 10 O 5 Pentose Aldohexose Glucose Ketohexose Fructose 1 2

8. Disaccharides Polysaccharides - C 12 H 22 O 11 E.g. Maltose, Sucrose - (C 6 H 10 O 5 ) n where n is a very large number E.g. Starch, Cellulose

9. Open chain and cyclic structures of glucose and fructose ++.. (Fischer projection) 1 5 6 1 5 6  -glucose  -glucose 5 1

10. The cyclic structures are more stable than the open chain structure The lone pair on -OH can attack the carbonyl carbon from above or below the plane leading to the formation of two isomers (  and  glucose).

11. Fructose.. 5 ++ 2 6 1 1 2 5 6  -furanose  -pyranose 1 2 6

12.  In the free state, fructose exists as pyranose (6-membered ring).  In disaccharides and polysaccharides, fructose exists as furanose (5-membered ring).

13. Disaccharides and Glycosidic linkage 2C 6 H 12 O 6 Condensation C 12 H 22 O 11 + H 2 O hydrolysis Glucose + Glucose Maltose + water Glucose + Fructose Sucrose + water

14. + 1 4 1,4-glycosidic linkage Maltose  -glucose

15. 2 52 5 Rotate 180 o  -fructose

16.  -glucose +  -fructose 1 1 2 1 2 1,2-glycosidic linkage Sucrose

17. Testing for reducing sugars  Reducing sugars - sugars that contain free aldehyde group  Give red ppt of Cu 2 O when treated with Fehling’s solution Complex ion of Cu 2+ + RCHOCu 2 O(s) Deep blueRed

18. All monosaccharides are reducing sugars ++.. (Fischer projection) 1 5 6 1 5 6  -glucose  -glucose 5 1 ~0.02% ~64%~36%

19. Fructose Glucose Fructose undergoes transformation to give glucose  Fructose is a reducing sugar

20. Maltose 1 5 The right ring is able to open to give a free aldehyde group which can be oxidized  A reducing sugar

21.  -glucose +  -fructose 1 1 2 1 2 1,2-glycosidic linkage Sucrose Both rings are locked  non-reducing sugar

22. Polysaccharides nC 6 H 12 O 6  -glucose Starch nC 6 H 12 O 6  -glucose Cellulose

23. Starch Amylose Amylopectin Amylose - consists of unbranched chains of  -glucose units joined by  -1,4 linkages Amylopectin - consists of highly branched chains of  -glucose units linked by  -1,4 linkages

24. Amylose 1,4 glycosidic linkages

25. 1 6 1 6 Amylopectin 1,6-glycosidic linkages

26. Cellulose : - consists of unbranched chains of  -glucose units joined by 1,4-glycosidic linkages the structural component of cell walls of plant

27. 1 4 41 4 1 1,4 - glycosidic linkages The 2nd unit is flipped over

28. Hydrolysis of Sucrose C 11 H 22 O 11 + H 2 OC 6 H 12 O 6 + C 6 H 12 O 6 H + or invertase glucosefructosesucrose [  ] D = +66. 5 o [  ] D = +52.7 o [  ] D = -92.4 o The reaction mixture undergoes an inversion in optical activity (from + to -) Laevorotatory (-) Dextrorotatory(+)

29. maltase C 12 H 22 O 11 + H 2 O2C 6 H 12 O 6 Glucose 2(C 6 H 10 O 5 ) n + nH 2 O amylase nC 12 H 22 O 11 Maltose Starch (C 6 H 10 O 5 ) n + nH 2 O H + nC 6 H 12 O 6 StarchGlucose Hydrolysis of Starch