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CARBOHYDRATES Foundation Module-Phase 1 Department of Biochemistry Faculty of Medical Sciences.

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Presentation on theme: "CARBOHYDRATES Foundation Module-Phase 1 Department of Biochemistry Faculty of Medical Sciences."— Presentation transcript:

1 CARBOHYDRATES Foundation Module-Phase 1 Department of Biochemistry Faculty of Medical Sciences

2 What are carbohydrates? Energy Aldehyde or ketone derivatives of polyhydric alcohol Formula (CH 2 O) n (n > 3) Not all carbohydrates have this empirical formula: deoxysugars, aminosugars used as an energy source and in making cell structures.

3 Sources of carbohydrate Rice Wheat Bread Biscuit Potato Oats

4 Do you know…. Q1: List the main functions of carbohydrates? Q2: How are carbohydrates classified? Answer

5 Types of Carbohydrates Based on the number of monomers. 1.Monosaccharides: 1 2.Disaccharides: 2 3.Oligosaccharides: Polysaccharides: more than 20 Back

6 Q3: How to classify monosaccharides? –According to the number of carbons –According to functional groups Aldosugars Ketosugars

7 Back

8 Back

9 Structure (Single Sugar Unit) Monosaccharide

10 Common Monosaccharides fructose (fruit sugar) galactose How to measure Glucose For your interest only

11 Properties of monosaccharides? A. Physical properties * Highly soluble in water * Most taste sweet B. Chemical properties * Formation of cyclic hemiacetals or hemiketals * New chiral center => 2 “anomers” designated  and 

12 C groups

13 Answers


15 v Chiral centers Penultimate OH group


17 Fisher projection Haworth projection Structural representation of sugars (straight chain representation) (simple ring in perspective)

18 Fisher projection Haworth projection

19 Disaccharides Sugars composed of two monosaccharides linked together by glycosidic bonds. e.g.Maltose

20 Common Disaccharides sucrose (table sugar) Commercially obtained from sugar cane or sugar beet

21 Used : as a nutrient (malt extract) as a sweetener as a fermentative reagent  (1,4) linkage maltose (seed sugar) Found in germinating grains

22 lactose (milk sugar) Refer: What is lactose intolerance?

23 Polysaccharides or glycans Complex carbohydrates that are made up of hundreds of monosaccharides linked by glycosidic bonds. Homoglycans Starch Cellulose Glycogen Inulin Heteroglycans Gums Mucopolysaccharides

24 Polysaccharides (Many sugar units)

25 Starch Test for starch? Answer

26 Suspensions of amylose in water adopt a helical conformation. Iodine (I 2 ) can insert in the middle of the amylose helix to give a blue color that is characteristic and diagnostic for starch. Identification of starch-Iodine test Back to question

27 Cellulose

28 X Control Test Following is the test results for 3 different sugars 1.Name the test 2.What is in X & Z? 3.What is in Y ? Answer Y

29 Barfoed’s test Following is the Barfoed’s test results for sugars. YX Tube Y contains ……….. a)Maltose b)Glucose c)Lactose Answer

30 Seliwanoff’s test Following is the Seliwanoff’s test results for sugars. XY Tube Y contains………. a)Glucose b)Maltose c)Fructose Answer

31 Back to the beginning

32 Q1- List the main function of carbohydrates Sources of energy Form structural components –cellulose, lignin, murein Molecular recognition – Blood group antigens Associated with other entities –DNA, RNA, glycosides, vitamins Back to the question

33 Q3:How to classify carbohydrates? Number of monomers Monosaccharides(1) Disaccharides(2) Oligosacchrides(2-10) Polysaccharides or glycans(>10) –Homopolysaccharides –Heteropolysaccharides –Complex carbohydrates

34 Glucose measurement methods Most are enzymatic methods –3 enzyme systems are currently used : Glucose oxidase Glucose dehydrogenase Hexokinase

35 Glucose oxidase methods: colorimetric method

36 Back to the question

37 Answer 1.Benedict’s test 2.Reducing sugar 3.Non reducing sugar Back 1.Barfoed’s test 2.Disaccharides 3.Monosaccharides Can have two sets of answers

38 b)Glucose (Barfoed’s test is positive for Monosaccharides only) Back to the question

39 c)Fructose (Seliwanof’s test is positive for Keto sugars) Back to the question

40 N0 Yes N0 Yes Back

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