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Macromolecules & Carbohydrates

Macromolecules & Carbohydrates. Lecture 3 Dr. Mamoun Ahram. Cell's weight. Subunits. Subunits: the small building blocks (precursors) used to make macromolecules Macromolecules: large molecules made of subunits. Macromolecules. Carbohydrates (monosaccharides) Proteins (amino acids)

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Macromolecules & Carbohydrates

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  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

  5. Relationship (monomers and polymers)

  6. 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”

  7. Carbohydrates

  8. Resource • This lecture • Campbell and Farrell’s Biochemistry, Chapter 16

  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 • By the number of sugars that constitute the molecule • 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

  14. Numbering carbons…again

  15. Numbering order of compounds with more than one functional group Carboxylic acid Aldehyde Ketone Alcohol Amine Alkyne = alkene Alkane

  16. Classification 2 • By the number of carbon atoms they contain • Triose • Tetrose • Pentose • Hexose • Heptose

  17. Trioses

  18. Glyceraldehyde Chiral carbon

  19. Isomerism

  20. Structural isomers • Same number of atoms, different connectivity

  21. Stereoisomers Same number of atoms and connectivity, but not superimposable

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

  23. Isomers of glucose

  24. Mirror images and non-superimposable, then…enantiomers

  25. Light polarization

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

  27. Which one(s) is a chiral carbon?

  28. Stereoisomers, but non-mirror images and non-superimposable, then…diastereomers OH H H OH

  29. Diastereomers that differ in the orientation of one chiral carbon…epimers

  30. Isomerism

  31. Formation of a ring structure

  32. Ring structures

  33. Example

  34. Acetal/ketal vs. hemiacetal/hemiketal Hemiacetal and hemiketal: ether and alcohol on same carbon Acetal and ketal: two ethers on same carbon What is the difference between hemiacetal and hemiketal and the difference between acetal and ketal?

  35. Hemiacetal vs. hemiketal

  36. Haworth vs. Fischer projections

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

  38. Anomers

  39. α vs β fructose

  40. - vs. -glucopyranose

  41. Cyclic fructose

  42. Cyclic aldohexoses

  43. Cyclic ribofuranose

  44. Modified sugars

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