1. Chapter 14 14.1 - Carbohydrates

2. Chemistry of Life

3. Making and Breaking Carbohydrates Making: photosynthesis in plants: glucose is synthesized from CO 2, H 2 O (reduction): energy comes from the sun Breaking: Cellular Respiration in plants and animals Glucose is oxidized to produce CO 2, H 2 O, energy released is used to form ATP

4. Types of Carbohydrates Monosaccharides: simplest carbohydrate, made of one monomer disaccharides, consist of two monosaccharides polysaccharides, contists of many monosaccharides

5. Hydrolysis Chemical reaction to separate polymers by inserting a water molecule

6. Monosaccharide variety Monosaccharides have anywhere between 3-6 carbons Can be simply named with molecular prefixes 3: triose 4: 5: 6:

7. Functional groups in sugars: Hydroxyls Sugars are poly-ols – molecules with multiple hydroxyl groups Chiral position of hydroxyls distinguishes one sugar from another Biological difference!

8. Functional groups: aldehydes, ketones Each sugar also contains either one aldehyde or one ketone group (this will be the highest oxydized carbon!) simple nomenclature aldose ketose

9. Naming Simple: Use C-number, aldehyde/ketone Complex: have individual names aldohexoseketohexose GlucoseFructose

10. Chapter 14 14.2 – Structure of Monosaccharides

11. Fischer Projections

12. Isomers of sugars Sugars are chiral molecules They exist as D- and L-forms: stereoisomers They have different 3D-structures and are biologically different molecules In nature 99% are D-forms

13. Identifying D and L Isomers Draw sugar vertical with highest oxidized carbon (aldehyde/keton) on top (C1/C2) Number all carbons from top to bottom The chiraI carbon furthest from the top determines D/L Hydroxyl points left: L Hydroxyl points right: D

14. D-Glucose Aldohexose other name: dextrose Found in fruits, vegis Is blood sugar molecule Building block of many di/polysaccharides: Memorize: ta,tu,ta,ta (sound of the German Fire Engine!)

15. D-Galactose Aldohexose Found in cellular membranes, brain Component of disaccharide lactose Differs from D-glucose in C #4

16. D-Fructose Ketohexose Other name fruit sugar Major sugar in fruits One of the sweetest cabohydrates

17. Memorize structure of these 3 monosaccharides

18. Chapter 14 14.3 – Cyclic Structures of Monosaccharides

19. Monosaccharides in Nature The linear form of monosaccharides is not very stable Pentoses and hexoses form rings to improve stability Hemiacetal: cyclical form of monosaccharides

20. Hemiacetals 99% ring : 1 % linear Sugars open and close randomly, frequently Glucose Ringclosure: Hydroxyl group on C5 connects to C1: 1,5 ether linkage. This is not a dehydration but a rearrangement: C5: OH transfers to C1 turning carbonyl =O into hydroxyl -OH

21. C1 :non-chiral in linear form but chiral in ring: labeled α or β

22. Numbering Carbons on Hemiacetals Always start on the right hand side 1,5 Ether Linkage

23. Cyclic Structure of Galactose Galactose is an aldohexose that differs from glucose only with the –OH group on carbon 4 With formation of a new hydroxyl group on carbon 1 – galactose also exists in α & β forms D-Galactose α -Galactose β -Galactose

24. Cyclic Structure of Fructose Fructose is a ketohexose: C5 reacts with ketone group C2 Smaller ring: pentagon

25. Fructose Ring numbering 2,5-ether linkage

26. Chapter 14 14.5 – Disaccharides

27. Linking Monosaccharides together Monosaccharides can react with each other to form di- and polysaccharides (only with rings) Dehydration Rx: involving the OH groups of two sugars, splitting out of a water molecule Formation of an ether linkage called glycosidic bond ( in sugars only!)

28. Glycosidic bond formation

29. Types and Naming of Glycosidic Bonds: Ex Maltose Carbon number of first sugar connected to Carbon number of second sugar: C1 to C4 C1 is α in this case Writing conventions: α -1,4 glycosidic bond alpha (1-4) “ α - (1,4) “

30. More examples

31. beta (1-4) glycosidic bond

33. 3 Disaccharides you need to know Maltose – malt sugar Lactose – milk sugar Sucrose - table sugar Characterized by 1. Type of monosaccharides 2. Type of glycosidic bond

34. Maltose Monomers: α-D-Glucose and α/β-D-Glucose Glycosidic bond: α (1-4) β-D-Maltose α-D-Maltose α/β of disaccharides is determined by the second sugar

35. Maltose – Malt Sugar Obtained from the hydrolysis of starch Used in cereals, candies, and brewing of beverages

36. Lactose Monomers: β-D-galactose and α-/β-D- glucose Glycosidic bond: β (1-4) β-D-Lactose α-D -Lactose

37. Lactose Makes up 6-8% of human milk and 4-5% of cow milk Lactose intolerance: lack of the enzyme lactase that splits disaccharide during digestion Adult Mammals stop expressing the lactase gene – exception: many adult humans have developed a lactose tolerance (microevolution) depending on ethnicity

38. Sucrose Monomers α-D-glucose and β-D-fructose Glycosidic bond: α,β (1,2) only one form of D-Sucrose

39. Sucrose Commercial sugar, obtained from sugar beets and sugar cane

40. Chapter 14 14.6 – Polysaccharides

41. Polysaccharides A polymer of many monosaccharides joined together: glycosidic bd Four important polysaccharides: Amylose/Amylopectin –plant starch Glycogen – animal starch Cellulose – plant fibers Monomers: all D-glucose but different glycosidic bonds

42. Starch glucose storage in plants Found in grains, potatoes, beans, fruits Soluble in water Commercial Starch: mixture amylose 20% and amylopectin 80%

43. Amylose Monomer: α-D-glucose (about 200-4000) Glycosidic bond: α-1,4-GB Enzyme: amylase Long helical chain

44. Amylopectin Monomer: α, D-Glucose Glycosidic Bond: α (1,4) and α (1,6) GB (every 25 glucose monomers) Enzyme: amylase isozyme “Branched starch”

45. Glycogen Animal starch Storage of glucose in the liver Similar to amylopectin only more branches (every 10-15 glucose molecules)

46. Cellulose Monomers: β,D- glucose Glycosidic bond: β1,4-glycosidic bonds Enzyme: Cellulase Insoluble in water straight strands, found in the cell wall of plants, make plant stalks rigid and strong Humans, animal, plants lack the enzyme cellulase only bacteria living in the guts of ruminants have cellulase

47. Cellulose Cotton, wood, insoluble in water

48. Digestion of Cellulose Grazing animals and termites harbor e-coli who digest cellulose for them In all other animals cellulose helps absorb toxins from digestion of proteins and maintain a healthy digestive system

49. Carbohydrates in Our Diet