1. Macromolecules& Carbohydrates Lecture 3 Dr. Mamoun Ahram

2. Cell's weight

3. Subunits • Subunits: the small building blocks (precursors) used to make macromolecules • Macromolecules: large molecules made of subunits

4. Macromolecules • Carbohydrates (monosaccharides) • Proteins (amino acids) • Nucleic acids (nucleotides) • Lipids (fatty acids) • Except for lipids, these macromolecules are also considered polymers

6. Relationship (monomers and polymers)

7. How water is removed? • Mechanism 1: One subunit contributes an “H” and the other subunit contributes an “OH” • Mechanism 2: One subunit contributes 2 “H” the other subunit contributes an “O”

8. Carbohydrates

9. What are they? • Carbohydrates are polyhydroxy aldehydes or ketones • Saccharide is another name for a carbohydrate

10. Functions • Source of energy • Structure (cellulose and chitin) • Building blocks • Cellular recognition

11. Classification I • Monosaccharides • Disaccharides • Oligosaccharides • Polysaccharides

12. Monosaccharides • Basic chemical formula: (CH2O)n • They contain two or more hydroxyl groups

13. Drawing sugars • Fisher projections or perspective structural formulas Forward Backward Top (C1): Most highly oxidized C

16. Numbering carbons…again

17. Classification 2 • By the number of carbon atoms they contain

20. Trioses

21. Glyceraldehyde Chiral carbon

22. Mirror images and non-superimposable, then…stereoisomers

24. Stereoisomers

25. This is different than structural isomers

26. Sugar enantiomers (D- vs. L-)

27. Which chiral carbon?

28. Number of possible stereoisomers • 2n (n is the number of chiral carbons in a sugar molecule)

29. Isomers of glucose

30. Diastereomers

31. Epimers

32. Formation of a ring structure

33. Hemiacetal vs. hemiketal

34. Haworth vs. Fischer projections

35. Ring structures

36. Example

37. Anomers

38. - vs. -glucopyranose

39. Cyclic fructose

40. Galactose

41. Fischer vs. HaworthLeft-right vs. up-down

42. Cyclic aldohexoses

43. Cyclic ribofuranose

44. Modified sugars

45. Sugar esters (esterification) • What is the reacting functional group? Where does it react? What are the end products? Where are they used?

46. Sugar acids (oxidation) • Where is it oxidized? What does it form?

47. Example 1

48. Example 2

49. Example 3

50. Note • Oxidation of ketoses to carboxylic acids does not occur