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Carbohydrate

Carbohydrate. Aulanni ’ am Laboratory of Biochemistry Brawijaya University. Six Classes of Nutrients. Carbohydrate Protein Fat Vitamins Minerals Water. Carbohydrates and Relation to Health. Dietary fiber and prevention of chronic diseases Carbohydrates and dental health

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Carbohydrate

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  1. Carbohydrate Aulanni’am Laboratory of Biochemistry Brawijaya University

  2. Six Classes of Nutrients • Carbohydrate • Protein • Fat • Vitamins • Minerals • Water

  3. Carbohydrates and Relation to Health • Dietary fiber and prevention of chronic diseases • Carbohydrates and dental health • Carbohydrates and diabetes Carbohydrates and weight loss???

  4. Carbohydrates and Prevention of Chronic DiseasesHealth Benefits of Fiber Reduce the risk of • Heart disease • Diabetes • Diverticular disease (gastrointestinal / GI) Other • Relieves Constipation • Hemorrhoids • Lowers the GI/GL • Makes you feel full

  5. Complex Carbohydrates Starch digestible plant polysaccharide Fiber indigestible polysaccharide residues of food • Cannot be broken down by human digestive enzymes • some broken down by bacteria in the digestive tract • few, if any, calories because not digested • Examples: cellulose, hemicellulose, pectin, gums Polysaccharide: long chain of 10 or more glucose molecules linked together; the chains can be straight or branched; another term for complex carbohydrates

  6. Dietary Fiber • Components of the cell walls of plants • cereal grains, fruits, vegetables • Polymer of monosaccharides • Human digestive enzymes cannot break down • Cellulose = ~3000 glucose

  7. Dietary Fiber - Two groups • Insoluble • fibers that mostly do not dissolve in water • not digested by bacteria in the large intestine • Soluble • fibers that either dissolve or swell in water or • are metabolized by bacteria in the large intestines

  8. Fiber Sources

  9. Degree of polymerization • Monosaccharides • Storage, energy modules, metabolic intermediates • Disaccharides, trisaccharides • Storage • Oligosaccharides • Molecular Recognition • Polysaccharides • Structure, storage

  10. Fisher Projectionsof chiral monosaccharides • Next-to-bottom carbon hydroxyl extends to the right --- a D sugar; cf. with L amino acid

  11. fig 9-3a

  12. fig 9-3b

  13. Hemiacetal/-ketal structures of monosaccharides • Reaction of an aldehyde or ketone with an alcohol • favorable intramolecular reaction

  14. fig 9-5

  15. Intramolecular hemiacetals/ketals of monosaccharides are RINGS stereo chair open chain Haworth

  16. Anomers • Sugars that vary in configuration about the anomeric (aldehydic or ketonic) carbon • Convention:  = hydroxyl down,  = hydroxyl up

  17. fig 9-6

  18. Fig 9-7

  19. Hexose derivatives • Amino sugars • Acetamido sugars • Deoxy sugars • Fucose, rhamnose, abequose • Other glycosidic additives • Lactic acid • Oxidized sugars • Sugar phosphates

  20. Fig 9-9

  21. Reducing sugars • Aldehydes are oxidized by mild agents • Cu2+ + aldehyde (or -hydroxyketone)  Cu+ + acid • Disaccharides react more slowly

  22. Fig 9-10

  23. Disaccharides • Glycosidic linkage • Acetal (or ketal) formed. 2nd monosaccharide acts as an alcohol

  24. Fig 9-5 (repeat)

  25. Reducing • one anomeric C not glycosidically linked • Nonreducing • Both anomeric C’s linked (fructose, trehalose)

  26. Disaccharide nomenclature • Nonreducing end on left • Linkage –(nm)- • Reducing end Note that nonreducing end configuration is fixed Reducing end can mutarotate, thus 1st component given as - or -, 2nd ambiguous (next slide)

  27. Fig 9-11

  28. Table 9-1

  29. Important disaccharides • Maltose • Lactose • Sucrose • Trehalose

  30. Fig 9-12

  31. Table 9-2

  32. Storage polysaccharides • Plants • Starch • Amylose – llinear polyglucose, -1,4 linked (-D-glucopyranosyl-(14)-…), M ~ 106 • Amylopectin –polyglucose, -1,4 linked, -1,6 branched 1 per 24-30, M ~ 108 • Animals • Glycogen • polyglucose, -1,4 linked, -1,6 branched 1 per 24-30, M ~ 106

  33. Fig 9-15 b

  34. Fig 9-14 0.10 m 1.0 m

  35. fig 9-15

  36. Structural Polysaccharides • Plants • Cellulose – linear polyglucose •  1,4 linked • M ~ 106 • Certain exoskeletons • Chitin – linear poly(N-acetyl-D-glucosamine) •  1,4 linked

  37. Fig 9-17a and 9-18 Cellulose Chitin

  38. Structural polysaccharides, cont • Bacterial cell walls – peptidoglycans • Extracellular matrix of multicellular animals - glycosaminoglycans

  39. Fig 9-19

  40. Fig 9-20

  41. Sugar-protein and sugar-lipid conjugates • Glycoconjugates • Proteoglycans • Glycosaminoglycans bound to proteins • Glycoproteins • Oligosaccharides bound to proteins • Glycolipids • Oligosaccharides bound to lipids (heads of membrane lipids)

  42. Fig 9-29

  43. Fig 9-27

  44. 2. Carbohydrates and Dental HealthDental Caries (Cavities) MECHANISM • Bacterial acid dissolves enamel • Carbohydrate serves as food for bacteria • Plaque on teeth – sugars stay in but acids don’t go out CARIOGENIC FOOD FACTORS • Fermentable – contains sugars • Sticky • Stays in mouth a long time (think taffy) Bacterial + Sugars Cavities

  45. 3. Carbohydrates and Diabetes Diabetes: An inability to regulate blood glucose levels • A disease in which an individual does not produce or properly use insulin • Results in: • abnormally high levels of glucose in blood • Because of: • lack or ineffectiveness of insulin • hormone that is needed to convert sugar, starches and other food into energy needed for daily life • the true cause continues to be a mystery, • although both genetics and environmental factors • such as obesity and lack of exercise play roles

  46. 5-10% of cases Pancreas unable to make insulin to meet needs Genetic predisposition + environmental factors Insulin injections Dietary Intervention Reduce the amount of simple sugars Eat foods w/ dietary fiber Person will lose weight 90-95% of cases Maybe insufficient insulin or cells maybe unresponsive to insulin Genetic predisposition + obesity Dietary intervention Weight loss intervention Person is always hungry Increase in obesity Type I vs. Type II Diabetes Type 1 – Insulin Dependent Type 2 – Non- Insulin Dependent Incidence Insulin Risk factor Treatment

  47. Carbohydrates role in blood glucose • A numerical system • Measures extent of rise in circulating blood sugar a carbohydrate triggers • GI number, blood sugar response Glycemic Index

  48. Glycemic Index estimate of how quickly food affects your blood sugar

  49. Glycemic Index High GI > 70 potatoes, white bread Low GI < 55 pasta, whole grain bread Not just about individual foods it’s about our diet

  50. Factors Influencing GI • Biochemical structure of the carbohydrate • Absorption process • Size of the food particle • Contents and timing of the previous meal • Co-ingestion of fat, fiber, or protein

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