1. Condensation of two  -amino acids to form a dipeptide. 1

2. N-Serine-Glycine-Tyrosine-Alanine-Leucine-C N-Ser-Gly-Tyr-Ala-Leu-C N-SGYAL-C 2

3. Sugars and Polysaccharides Carbohydrates: carbon hydrates (CH 2 O) n or C n O n H 2n Monosaccharides : n≥3, polyhydroxy aldehydes and polyhydroxy ketones (single unit). Essential components of all living organisms. -Aldose: aldehydic carbonyl or potential aldehydic carbonyl group -Ketose: ketonic carbonyl or potential ketonic carbonyl group Saccharides are also important components of nucleic acids, glycoproteins proteins and complex lipids. 3

4. Glyceraldehyde contains one chiral center* at C-2. In general n carbon aldoses contain 2 n-2 stereoisomers. Dihydroxyacetone the simplest ketose, does not contain an chiral center Erythrulose, the second sugar in the ketose series, contains one chiral center at C-3. In general n carbon ketoses contain 2 n-3 stereoisomers 123123 123123 12341234 4

5. Nomenclature : - Fischer convention : D sugars have the same absolute configuration at the stereogenic center farthest removed from their carbonyl group as does D-glyceraldehyde. - The L version of the sugars are the mirror image of their D counterparts 5

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7. D-Arabinose D-Xylose 7

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9. D-Erythrulose 9

10. 10

11. L sugars are biologicaly much less abundant than D sugars. Know the structures of the sugars whose names are boxed. Aldoses to remember are: D-glyceraldehyde, D-erythrose, D-ribose, D- mannose, D-galactose, D-glucose Ketoses to remember are: Dihydroxyacetone, D-ribulose, D-xylulose, D- fructose 11

12. Epimers 12

13. 13

14. The reactions of alcohols with (a) aldehydes to form hemiacetals and (b) ketones to form hemiketals. Configurations and conformations Sugars can exist in several cyclic conformations, this is a consequence of the intrinsic chemical reactivity of the functional groups in the corresponding sugar Intramolecular reactions 14

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17. -The ring closure process renders the former carbonyl group asymetric: !!!! New chiral center !!!! -The newly generated pair of diastereomers are call anomers and the hemiacetal/ketal carbon is call anomeric carbon  anomer : OH substituent at the anomeric carbon is in the opposite side of the sugar ring from the CH 2 OH group at the chiral center that designates the D or L configuration  anomer : OH substituent at the anomeric carbon is in the same side of the sugar ring from the CH 2 OH group at the chiral center that designates the D or L configuration 17

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19. After dissolution in water: D-Glucose: Exclusively pyranose D-fructose: 67% pyranose, 33% furanose D-ribose: 75% pyranose, 25% furanose However, in polymers: Glucose: pyranose Fructose: furanose Ribose: furanose All the interconversions between furanose and pyranose form proceed through the linear form of the molecule. D-glucose is 33%  and 66%  19

20. Sugars are conformationally variable 20

21. 2 forms of  glucose 21

22.  glucose  glucose D-glucose is 33%  and 66%  22

23. Monosaccharides are modified 23

24. Monosaccharides are modified 24

25. Aldonic AcidAldose Uronic Acid Glucose Gluconic AcidGlucuronic Acid Oxidation reduction reactions : The aldehyde moiety in aldoses can be oxidize to yield a carboxylic acid, the resulting compounds are known as aldonic acids. 25

26. Monosaccharides are modified 26

27. Ribose Ribitol - The reduction of the carbonyl group in aldoses and ketoses yields polyols known as alditols 27

28. Glycerol Inositol 28

29. Gulose Gulonic Acid Gulono-  -lactone Glucose Gluconic Acid Ascorbic acid 29

30. Dehydroscorbic acid Ascorbic acid + 2e- 30

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32. Sugar derivatives: The chemistry of sugars is largely that of their hydroxy and carbonyl groups. Glycosidic bonds: are analogous to the peptide bond in proteins, polysaccharides; are held together by glycosidic bonds between neigboring monosaccharides units 32

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34. 1 2 3 4 5 6 1 2 3 4 5 6  -glucose  -glucose  -glucose-(1,4)-  -glucose glucose-(  )-glucose 34

35.  -glucose-(1,4)-  -glucose glucose-(  )-glucose 35

36.  -glucose-(1,4)-  -glucose glucose-(  )-glucose 36

37.  -glucose-(1,6)-  -glucose glucose-(  )-glucose 37

38. Trehalose  -glucose-(1,1)-  -glucose glucose-(  )-glucose 38

39.  -galactose-(1,4)-  -glucose Galactose-(  )-glucose 39

40.  glucose-(1,4)-  -fructose glucose-(  )-fructose 40

41. Polysaccharides 41

42. Rigid - used for osmotic protection Load bearing function Cellulose Polysaccharides 42

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44. Degrading cellulose 10 15 kg of cellulose synthesized and degraded annually Disaccharide product of breakdown is cellobiose Only microbes can do this! 44

45. Exoskeltons for invertebrates Chitin 10 14 kg of chitin synthesized and degraded annually  (1,4)-N-acetylglucosamine 45

46. Storage Polysaccharides Starches Amylose Amylopectin Glycogen 46

47.  (1 - 4) Amylopectin Branched every 24 to 30 sugars 47

48. Amylose Amylopectin 48

49. Structure of glycogen. More extensively branched (every 8-12 sugars) Disaccharide breakdown products of starch are maltose and isomaltose 49

50. Cell Walls and Connective Tissue 50

51. Cell Walls and Connective Tissue 51

52. Lubricant for joints, “jelly” in the eye 52

53. Tensile strength in joints, heart 53

54. Horns, hair, hoofs, nails, claws 54

55. Anticoagulant 55

56. 56

57. Model of oligosaccharide dynamics in bovine pancreatic ribonuclease B (RNase B). 57