Carbohydrate Chemistry Lecture Notes PDF

They are one of three major organic compounds in living organisms Carbohydrates Lipids Proteins Definition Carbohydrates are aldehydes or ketones derived from polyhydric alcohols O and H present in same proportion as in water 2:1  Glycerol...

They are one of three major organic compounds in living organisms Carbohydrates Lipids Proteins Definition Carbohydrates are aldehydes or ketones derived from polyhydric alcohols O and H present in same proportion as in water 2:1  Glycerol CHOH Aldehyde Ketone 1. Major source of energy: as glucose and glycogen. 2. Structural material: in plants (cellulose). 3. Biosynthesis of essential compounds: as purines, pyrimidines (DNA and RNA). 3. Membrane structure: Glycolipids and glycoproteins Classification 1- Monosaccharides (simple sugars) as glucose. 2- Oligosaccharides 2 - 10 monosaccharide units linked together as sucrose. 3- Polysaccharides > 6 monosaccharides linked together as glycogen.  Classification of Monsaccharides 1- Number of carbon atoms No of Name Carbons Triose: Glyceraldehyde and 3 dihydroxy acetone 4 Tetrose: Erythrose 5 Pentose: Ribose Hexose: glucose, galactose, 6 mannose and fructose  Numbering of carbon atoms Beginning at end of chain nearest carbonyl group. 1 1 2 2 3 3 4 4 5 5 6 6 Glucose Fructose  D-Glucose Present in fruits and vegetables Grape sugar Produced by hydrolysis of starch Concentration in blood 100 mg/dl.  D-Fructose Fruit sugar. Very sweet sugar. Main sugar in semen. Itpresents in disaccharide (sucrose) and polysaccharide (inulin).  D-Galactose Present in lactose of milk Less sweet than glucose. Enter in structure of galactolipids D-Mannose Enter in structure of glycoproteins  Monosaccharide Derivatives Sugar acids: oxidized sugars Sugar alcohols: reduction of sugars Deoxy sugars: in DNA Sugar esters: phosphate esters as ATP Amino sugars contain amino group in place of OH group Glycosides: in oligo- and poly- saccharides Oligosaccharides Oligosaccharides are formed from 2 - 10 sugar units linked together by a glycosidic linkage. These includes; Disaccharides, trisaccharides, polysaccharides Disaccharides : They are glycosides formed by the condensation of 2 simple sugar units. The most common disaccharides are; Sucrose, Lactose, and Maltose.  Polysaccharides HomoPolysaccharides HeteroPolysaccharides Branched Unbranched  Branched Homopolysacchrides Amylopectin and Glycogen  Polysaccharides Starch Glycogen Cellulose  Functions 1.Starch and glycogen are storage molecules 2.Chitin and cellulose are structural molecules  Starch Amylose Amylopectin Linear polymer branched Digestion of starch occurs in stages: to dextrins and to maltose to glucose  Glycogen Glycogen form 10% of liver and 1- 2% of muscle The only difference from starch is the number of α(16) branches is more.  Cellulose 1- Structure Consists of long non branching chain of b-glucose linked with b-(1-4) 2- Source of cellulose It is present in plants as wood and cotton Digestion of cellulose The enzyme that can digest β (1-4) bond is not present in human, so it can’t be digested. It is digested in herbivorous animals that have this enzyme. So, cellulose passes in stool and prevent constipation So persons feed starch grows well as starch is digested inside the body while person intakes cellulose starves, as cellulose is not digested and will not produce energy for the body. Heteropolysaccharides Glucosaminoglycans Glycoproteins Glycolipids