5Tahir Carbohydrates IHS by TA series.pptx

Carbohydrates  References 1. Jacob A. (2004). Biochemistry for Nurses, 2nd ed. New- Delhi: Jaypee Brothers. 2. Chatterjea MN. (2004) Textbook of Biochemistry for dental /nursing /pharmacy students 2nd ed, New Delhi : jaypee. 3. Sackhiem, G. I. (1994).In Chemistry for...

Carbohydrates  References 1. Jacob A. (2004). Biochemistry for Nurses, 2nd ed. New- Delhi: Jaypee Brothers. 2. Chatterjea MN. (2004) Textbook of Biochemistry for dental /nursing /pharmacy students 2nd ed, New Delhi : jaypee. 3. Sackhiem, G. I. (1994).In Chemistry for the health science, 7 ed ,New York: Macmillan. 4. Tortora, F. J., & Anagnostakos, N.P. (2000). Principles of Anatomy & Physiology, New York: Harper & Row. 5. Lehninger N. I (1997) Principles of Biochemistry, 2nded, New York:Worth.  Course Contents Structure of Carbohydrates Classification of Carbohydrates Properties of Carbohydrates Biological significance of Carbohydrates Unit IV: Chemistry of Carbohydrates Describe the structure, properties & functions of Carbohydrates After the completion of this unit students will be able to: 1. Define carbohydrates. 2. Describe the general structure of carbohydrates. 3. Explain the classification of carbohydrate. 4. Compare the three major classes of carbohydrates that is monosaccharide, disaccharide and polysaccharide. 5. Discuss the biological significance of carbohydrates.  Objectives After the completion of this unit students will be able to: 1.Define carbohydrates. 2.Describe the general structure of carbohydrates. 3.Explain the classification of carbohydrate. 4.Compare the three major classes of carbohydrates that is mono saccharide, disaccharide and polysaccharide. 5.Discuss the biological significance of carbohydrates.  Carbohydrates Carbohydrate literary means hydrated carbon. Cn(H2O)m Carbohydrates are composed of carbon, hydrogen and oxygen The ratio of hydrogen and oxygen is the same as in water. Carbohydrates are – polyhydroxy aldehydes or – Polyhydroxy ketones or – complex substances that on hydrolysis yield poly(OH) aldehydes/ketones  Exceptions General formula: Cm (H2O)n Carbohydrates with different formula Uronic acids: C6H9O7 Fucose: C6H12O5 Noncarbohydrates with formula of carbohydrates Formaldehyde: CH2O Inositol: C6(H2O)6  Examples of Carbohydrates Glucose: major metabolic fuel of mammals Glycogen: storage; in animals Starch: Storage; in plants Cellulose: structure; plants;paper Chitin: stucture; in Arthropods Ribose: RNA, ATP, NAD Deoxyribose: DNA lactose: Milk Comparison of Carbohydrates Sweets Food high in carbohydrates Soft drinks Breads Beans, peas Cereals, Rice, maize, barley, wheat, corn apricot, dates, blueberry, banana, fig, grapes, apple, orange, pear, pineapple, strawberry, watermelon and raisins macaroni, spaghetti, potato, carrot  Functions Carbohydrates have six major functions within the body: Providing energy and regulation of blood glucose Sparing the use of proteins for energy Breakdown of fatty acids Biological recognition processes Flavor and Sweeteners Dietary fiber  Carbohydrate is necessary for the regulation of nerve tissue and is the source of energy for the brain. Some carbohydrates are high in fibre, which helps prevent constipation Structural components Carbohydrates are also important for the correct working of our brain, heart and nervous, digestive and immune systems. Polysaccharides: storage of energy (e.g., starch and glycogen), structural components (e.g., cellulose in plants and chitin in arthropods). ribose in coenzymes (e.g., ATP, FAD, and NAD) and the backbone of RNA. Deoxyribose: component of DNA. Heparin is used to treat and prevent blood clots from forming, especially in the lungs and legs. Classificat ion Monosaccharides  Monosaccharides They are simplest, colorless, water soluble, sweet, crystalline solids They can be classified according to four different ways 1. Placement of C=O group (Aldo, Keto) 2. The number of Carbon atoms (tri, tetra, penta) 3. Chiral Carbon handedness (D, L) 4. Rotation of plane polarized light (d, l)  Classification No. 1 Placement of CO group 1. Aldoses: Aldehyde group 2. Ketoses: Ketone group  Number of carbon atoms Diose: Glycolaldehyde Trioses: Glyceraldehyde, Dihydroxyacetone Tetroses: Erythrose, Erythrulose Pentoses: Ribose, Ribulose Hexoses: Glucose, Fructose Heptoses: Sedoheptulose, Mannoheptulose, Octoses: Methylthiolincosamide Nonoses: Neuraminic acid, Sialic acid Aldotriose: Triose Aldoses (ose) Aldotetrose:Tetroses Alodpentose: Pentoses Aldohexose: Hexoses Ketotriose: Triulose Ketoses (ulose) Ketotetrose: Tetrulose Ketopentose: Pentulose Keto Hexose: Hexulose Disaccharides (Glycosidic bond)  Mono and di ends in (ose) Mono and di also called sugars Blood sugar: Glucose Table sugar: Sucrose= Glucose+fructose Milk sugar: Lactose=Galactose+glucose Malt sugar: Maltose: Glucose+glucose  Isomerism In chemistry, isomers (isos = "equal", méros = "part") are compounds with the same molecular formula but different structural formulas. Structural Isomerism Stereoisomerism Link to the video is given in the description about isomerism  Stereoisomerism Same structural formula differ in spatial configuration with respect to the Penultimate Carbon atom glucose has 2 stereoisomers – D-glucose and – L-glucose Stereoisomerism  Enantiomers Mirror images, non superimposible  Diastereomers Non mirror images and non superimposible  Epimers Change in conformation around only one carbon  2D representation of a 3D structure As we know that molecules have 3D structures The paper\board allow us to draw only 2D structures We cannot draw 3D structures on a plane paper Fischer projection: For open chain Natta projection: For more accurate representation Haworth projection: For ring isomers of sugars Fischer projection  Fischer projection The Fischer projection is a two-dimensional representation of a three-dimensional organic molecule by projection.  Rules All bonds: horizontal or vertical lines. carbon chain: vertical (carbon atoms in center) C1: top. In an aldose, carbon of the aldehyde: C1 ketose the carbon of the ketone: lowest number horizontal bonds: toward the viewer vertical bonds away from the viewer.  Haworth projections A Haworth projection is a common way of representing the cyclic structure of monosaccharides with a simple three- dimensional perspective.  A Haworth projection has the following characteristics Atoms numbered 1 to 6: carbon atoms Carbon 1: Anomeric Carbon. Atoms 1 to 6 have extra hydrogen atoms not depicted. A thicker line: closer to the observer. 2 and 3 ( OH) Atoms 1 and 4: farther from the observer. 5: farthest. Groups below the plane of the ring: equivalent to right- hand side of a Fischer projection.  Cyclic isomers 1 CHO H C OH 2 HO C H D-glucose 3 H C OH (linear form) 4 H C OH 5 CH2OH 6 6 CH2OH 6 CH2OH 5 O 5 O H H H OH H H 4 H 1 4 H 1 OH OH OH OH OH H 3 2 3 2 H OH H OH -D-glucose -D-glucose  Anomers Alpha Beta  Reducing Sugar A reducing sugar is any sugar that is capable of acting as a reducing agent because it has a free aldehyde group or a free ketone group. All monosaccharides are reducing sugars, along with some disaccharides, some oligosaccharides, and some polysaccharides.  The monosaccharides can be divided into two groups: the aldoses, which have an aldehyde group, and the ketoses, which have a ketone group. Ketoses must first tautomerize to aldoses before they can act as reducing sugars. Disaccharides are formed from two monosaccharides and can be classified as either reducing or nonreducing. Nonreducing disaccharides like sucrose and trehalose have glycosidic bonds between their anomeric carbons and thus cannot convert to an open-chain form with an aldehyde group; they are stuck in the cyclic form. Reducing disaccharides like lactose and maltose have only one of their two anomeric carbons involved in the glycosidic bond, while the other is free and can convert to an open-chain form with an aldehyde group.  Reducing sugars Having an aldehyde group in open chain form Mono: Glucose, fructose, glyceraldehyde, galactose Di: Lactose, Maltose Di: Non reducing: Sucrose, trehalose  Hemi vs full acetal and ketal Hemiacetal Hemiketal acetal ketal Carbohydrates BScN (Lecture 6)  Physical Properties Mono and Disaccharides are crystalline solids Polysaccharides are amorphous solids Mono and Disaccharides are soluble in water Polysaccharides are insoluble in water Mon and Disaccharides are sweet in taste Polysaccharides are tasteless Mono and Di are low molecular weight Poly are high molecular weight  Chemical Properties Formation of Glycosides: In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. + CH OH + HO 3 CH H 3  Chemical Properties Osazone formation with phenlyhydrazine Osazone Formation Mechanism Shows positive test for: Benedict’s test Reducing sugars Reactions: Reducing sugars are oxidized by the copper ion in solution to form a carboxylic acid and a reddish precipitate of copper (I) oxide.  Fehling’s Test Fehling's can be used to distinguish aldehyde vs ketone functional groups. The compound to be tested is added to the Fehling's solution and the mixture is heated. Aldehydes are oxidized, giving a positive result, but ketones do not react, unless they are alpha-hydroxy-ketones. These tests are useful to check for glucose in the urine of a diabetics  Oxidation It is also possible to oxidize a monosaccharide to a carboxylic acid. – There are two important oxidations: oxidation of an aldehyde (aldose) to an aldonic acid, oxidation of the alcohol on the highest-numbered carbon atom to a uronic acid.  Ester Formation Monosaccharides, like all alcohols, may react with acids to form esters. Any of the alcohol groups may react. Glycosidic bond formation  Bacterial Cell Wall The cell wall is a – tough, – flexible – but sometimes fairly rigid layer – that surrounds some types of cells. It is located outside the cell membrane and provides these cells with – structural support and – protection, – in addition to acting as a filtering mechanism. A major function of the cell wall is to act as a pressure vessel, preventing over-expansion when water enters the cell. Cell walls are found in – plants, – bacteria, – fungi, – algae, and – some archaea. Animals and protozoa do not have cell walls.  The material in the cell wall varies between species, and can also differ depending on cell type and developmental stage. In bacteria, – peptidoglycan forms the cell wall. Archaean cell walls have various compositions, and may be formed of – glycoprotein S-layers, – pseudopeptidoglycan, or – polysaccharides. Fungi possess cell walls made of the – glucosamine polymer chitin algae typically possess walls made of – glycoproteins and – polysaccharides. Thank You