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CHEMISTRY OF CARBOHYDRATES

CHEMISTRY OF CARBOHYDRATES. Dr. Vinitha Ramanath Pai Professor Dept. of Biochemistry, YMC. CHEMISTRY OF CARBOHYDRATES. Class I August 13, 2018. Introduction. Carbohydrates are……. Widely distributed in plant and animal kingdoms

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CHEMISTRY OF CARBOHYDRATES

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  1. CHEMISTRY OF CARBOHYDRATES Dr. VinithaRamanathPai Professor Dept. of Biochemistry, YMC

  2. CHEMISTRY OF CARBOHYDRATES Class I August 13, 2018

  3. Introduction Carbohydrates are…….. • Widely distributed in plant and animal kingdoms • One of the most abundant class of bio - molecules in nature • Functions : Structural role and Metabolic role.

  4. Introduction What are carbohydrates ? Organic compounds i.e., compounds of carbon Formula : Cn(H2O)n Hydrates of carbon

  5. Class ISpecific learning objectives of this class • To define carbohydrates • To enlist the importance of carbohydrates • To classify carbohydrates with examples for each class, subclass

  6. What are the atoms present in carbohydrates Atoms : Main C, H and O. Some also contain N, P or S. Fructose Glucose

  7. What are the functional groups in carbohydrates ? Aldehyde Keto Hydroxyl groups - more than one Polyhydroxy And also contain either an Aldehyde or a Keto group Fructose Glucose

  8. Specific learning objective 1 : Definition Carbohydrates are…….. • Polyhydroxyaldehydes or Polyhydroxyketones, or compounds which give them on hydrolysis. • Polyhydroxy alcohols with free or potentially free aldehyde / keto groups or compounds which yield these on hydrolysis.

  9. Biological Importance of carbohydrates Carbohydrates have structural and metabolic functions Metabolic functions • Carbohydrates and energy : • Main source of metabolic energy in the body, e.g., Glucose • Storage forms of energy, e.gs., Starch in plants Glycogen in animals • Ribose is a component of ATP (energy coin of the cell) Specific learning objective 2 : Enlist the Importance of carbohydrates

  10. Biological Importance……Metabolic functions………. • Dietary fibre, e.gs., cellulose, hemicellulose, and pectins • Detoxification of drugs and bilirubin, e.g., Glucuronic acid • Synthesis of other compounds, i.e., lipids and amino acids - from the carbon skeletons of carbohydrates.

  11. Biological Importance……. Carbohydrates have the following structural functions • Components of structural biomolecules and cell membranes : • Mucopolysaccharides of ground substances of tissues, synovial fluid of joints, etc. • Glycoproteins of blood group antigens, • Glycoproteinsandglycolipidsof cell membranes, • Cellulose of plants, • Chitin of insects, etc.

  12. Biological Importance……. Carbohydrates have the following functions • Components of biomolecules : • e.gs. : In nucleic acids: Ribose in RNA and Deoxyribose in DNA • Nucleotides, e.g., ATP , cAMP contain Ribose

  13. Medical Importance: • Some important disorders associated with carbohydrates are- • Diabetes mellitus, • Lactose intolerance, • Galactosemia, • Glycogen storage diseases and, • Mucopolysaccharidoses.

  14. Medical Importance…… • Carbohydrate containing drugs (glycosides) are important in Therapeutics. • Antibiotics, e.g., Streptomycin, e.g., 1. cardiac glycosides. • Function : Agents whichincrease contractility of heart muscle. • Use : treatment of tuberculosis

  15. Specific learning objective 3 : Classification of Carbohydrates – into classes, sub-classes with suitable examples

  16. Classification of Carbohydrates • 3 classes • Basis : No. of monosaccharide units present / got on hydrolysis Carbohydrates 3 classes • MonosaccharidesOligosaccharidesPolysaccharides • Made up of more than 10 monosaccharide units • Single unit, i.e., • single chain of 3 – 7 Carbon atoms • Made up of 2 – 10 monosaccharide units

  17. Sub-classification of monosaccharides • Monosaccharides are single units, i.e., single chain of 3 – 7 carbon atoms • Class : Monosaccharides • sub-classified in 2 ways • 1. Based on the functional group present • 2. Based on the no. of carbon atoms present

  18. 1st Sub-classification of monosaccharides • Class : Monosaccharides • Based on the functional group present • Based on the no. of carbon atoms present • Aldoses • Aldehyde functional group • Ketoses • Keto functional group • E.g., Fructose • E.g., Glucose

  19. 2nd Sub-classification of monosaccharides • Class : Monosaccharides • Based on the functional group present • Based on the no. of carbon atoms present • 3C • 4C • 5C • 6C • 7C • Trioses • Tetroses • Pentoses • Hexoses • Heptoses

  20. Sub-classification of monosaccharides • Based on the no. of carbon atoms present • Examples • 3C • 4C • 5C • 6C • 7C • Trioses • Tetroses • Pentoses • Hexoses • Heptoses • GlyceraldehydeDihydroxyacetone • ErythroseErythrulose • Ribose Ribulose • Glucose Fructose • AldoheptoseSedoheptulose

  21. Identify the sub-class based on the no. of carbon atoms Identify the sub-class based on the functional group Aldose Ketose Hexose Aldohexose Aldose Tetrose Ketotetrose Aldotriose Triose Ketose Ketopentose Pentose Ketose Triose Ketotriose

  22. Combining the two classifications , monosaccharides are named as follows : Class activity Instruction : Create this table combining the two classifications of monosaccharides

  23. Classification of Oligosaccharides with examples Carbohydrates Class : Oligosaccharides (made up of 2-10 monosaccharides) Disaccharides Trisaccharides Others 2 monosaccharides 3 monosaccharides Examples : Maltotriose Raffinose Examples : Maltose Lactose Sucrose

  24. Sub -classification of oligosaccharides Disaccharides - made up of 2 monosaccharides Trisaccharides - made up of 3 monosaccharides Tetrasaccharides - 4 monosacccharides • Pentasaccharides - 5 monosacccharides • Hexasaccharides - 6monosacccharides Others

  25. Glycosidic bonds • Glycosidic bonds : Is the bond which links monosaccharides in oligosaccharides and polysaccharides. Formation : formed by dehydration between two hydroxyl groups on two monosaccharides.

  26. Sub -classification of dissacharides with examples Definition of Dissacharides Two monosaccharides linked by one glycosidic bond • Basis : Reducing property Sub class : Disaccharides 2 sub sub classes • Reducing disaccharidesNon reducing disaccharides • Reduce cupric ions to cuprous ions • Do not reduce Cu++ to Cu+ • Eg : Maltose; Lactose • Eg : Sucrose; Trehalose

  27. Sub -classification of polysaccharides with examples Definition of Polyssacharides More than ten monosaccharides linked by glycosidic bonds • 2 sub - classes • Basis : Type of monosaccharides got on hydrolysis Class : Polysaccharides 2 sub classes • HomopolysaccharidesHeterpolysaccharides • Same type of monosaccharide units • Different types of monosaccharide units • Eg : Hyaluronic acid, • Chondroitin sulfate • Eg : Starch, glycogen

  28. IInd Sub -classification of polysaccharides with examples • 2 sub - classes • Basis : On the function of the polysaccharide Class : Polysaccharides 2 sub classes • Nutritional polysaccharide Structural polysaccharides • Eg : Hyaluronic acid, • Chondroitin sulfate • Eg : Starch, • Glycogen

  29. Assignment of this class • Classification of carbohydrates with examples for each class/ subclass in the form of a flow chart. References: 1. D.M. Vasudevan - Textbook of Biochemistry for Medical Students. 2. U. Satyanarayana – Biochemistry. 3. Harper's Illustrated Biochemistry. 30th edition. Victor W. Rodwell, David A. Bender, Kathleen M. Botham, Peter J. Kennelly, P. Anthony Weil.

  30. Topic for self-directed learning for the next class • (i) Definition and examples for : • Isomers, • Isomerism, • Asymmetric carbon (chiral carbon) • (ii) Types of isomerism : • Functional /Geometrical/Stereo isomerism and • Optical isomerism

  31. Chemistry of carbohydrates IInd class 14 August 2018

  32. Review of the previous class • Defined carbohydrates • Enlisted the importance of carbohydrates • Classified carbohydrates with examples for each class/ subclass

  33. Class IISpecific learning objectives of this class To study the general characteristics of monosaccharides To study the types of stereoisomerism in monosaccharides and their importance • To list the derivatives of monosaccharides and their importance

  34. Class IISpecific learning objectives I To study the general characteristics of monosaccharides (as part of the introduction)

  35. Introduction to monosaccharides • General information of monosaccharides • Single chain of carbon atoms • Numbering of the carbon atoms • Ring structures of monosaccharides • Examples of monosacchaarides • Naming keto sugars.

  36. Introduction to monosaccharides • Monosaccharidesare the ……. • Simplest carbohydrates • Have single chain of carbon atoms (3- 7 carbons) • The basic units of all carbohydrates • Hydrolysis products of oligosaccharides and polysaccharides. • Empirical formula is Cn(H20)n. (n = no. of carbon atoms) • Mono-and disaccharides are referred to as ‘sugars’ - they are sweet to taste (Greek: saccharon means sugar).

  37. Monosaccharides have single chain of carbons Fructose Glucose

  38. Numbering carbon atoms in Monosaccharides * starts from the carbonyl (C=O) end. The carbonyl carbon atom in Aldoses is C1 Ketoses is C2. 1 1 * 2 2 3 3 4 4 5 5 6 6 Fructose Glucose

  39. Ring structure of Monosaccharides • In aqueous solution, monosaccharides containing 5 or more carbon atoms exist mostly as ring structures – • either 5 membered ring - furanose ring • or 6 membered ring - pyranose ring

  40. Straight chain structure Structure of Monosaccharides 6 1 5 2 4 1 3 3 2 4 5 6 membered ring - pyranose ring e.g., Glucose; Galactose; Mannose ALDOHEXOSES 6 Glucose

  41. Straight chain structure Structure of Monosaccharides 1 6 1 2 5 2 3 4 3 4 5 membered ring - furanose ring e.g., Fructose (KETOHEXOSE); Ribose; Deoxyribose; Xylose ALDOPENTOSE 5 6 Fructose

  42. Examples for the monosaccharides

  43. Naming of Keto sugars • The names end in ‘ulose’ • Examples : • Erythrulose • Ribulose • Xylulose • Sedoheptulose

  44. Quiz ahead …………….. • 5 multiple choice questions……. • (Answers on slide 38)

  45. Quiz Question 1 : Find the odd one in this group Dihydroxy acetone Ribulose Mannose Fructose • c) Mannose • It is an Aldose

  46. Quiz Question 2 : Which of these has a aldehyde functional group and five carbon atoms Glucose Ribulose Erythrulose Xylose • d) Xylose • It is an Aldopentose

  47. Quiz Question 3 : An example for a carbohydrate with no nutritional value is Starch Pectin Glycogen Glucose • b) Pectin • It is a dietary fibre

  48. Quiz Question 4 : Ribose and Xylulose are Pentoses Hexoses Aldoses Ketoses • a) Pentoses • They are aldopentose and ketopentose, respectively 49

  49. Quiz Question 5 : Which of these is a structural homopolysaccharide Starch Chitin c) Glycogen d) Hyaluronic acid • b) Chitin • Made up of N-Acetylglucosamine

  50. Intermediates of Glycolysis Important monosaccharides and their importance Ribose is found in RNA and Deoxy ribose is found in DNA; Nucleotides, cAMP Intermediates of HMP Shunt pathway Principal blood sugar and main source of energy (Dextrose) Main sugar in Honey Fruit sugar, (Levulose)

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