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Chapter 5

Chapter 5. The Structure and Function of Large Biological Molecules. You Must Know. The role of dehydration synthesis in the formation of organic compounds and hydrolysis in the digestion of organic compounds.

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Chapter 5

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  1. Chapter 5 The Structure and Function of Large Biological Molecules

  2. You Must Know • The role of dehydration synthesis in the formation of organic compounds and hydrolysisin the digestion of organic compounds. • How to recognize the 4 biologically important organic compounds (carbs, lipids, proteins, nucleic acids) by their structural formulas. • The cellular functions of all four organic compounds. • The 4 structural levels of proteins • How proteins reach their final shape (conformation) and the denaturingimpact that heat and pH can have on protein structure

  3. ie. amino acid  peptide  polypeptide  protein larger smaller

  4. + H2O + + H2O +

  5. I. Proteins • “Proteios” = first or primary • 50% dry weight of cells • Contains: C, H, O, N, S Myoglobin protein

  6. Protein Functions (+ examples) • Enzymes (lactase) • Defense (antibodies) • Storage (milk protein = casein) • Transport (hemoglobin) • Hormones (insulin) • Receptors • Movement (motor proteins) • Structure (keratin)

  7. Overview of protein functions

  8. Overview of protein functions

  9. Four Levels of Protein Structure • Primary • Amino acid (AA) sequence • 20 different AA’s • peptide bonds link AA’s

  10. Amino Acid • R group = side chains • Properties: • hydrophobic • hydrophilic • ionic (acids & bases) • “amino” : -NH2 • “acid” : -COOH

  11. Four Levels of Protein Structure (continued) • Secondary • Gains 3-D shape (folds, coils) by H-bonding • Alpha (α) helix, Beta (β) pleated sheet

  12. Basic Principles of Protein Folding • Hydrophobic AA buried in interior of protein (hydrophobic interactions) • Hydrophilic AA exposed on surface of protein (hydrogen bonds) • Acidic + Basic AA form salt bridges (ionic bonds). • Cysteines can form disulfide bonds.

  13. Four Levels of Protein Structure (continued) • Tertiary • Bonding between side chains (R groups) of amino acids • H bonds, ionic bonds, disulfide bridges, van der Waals interactions

  14. Four Levels of Protein Structure (continued) • Quaternary • 2+ polypeptides bond together

  15. amino acids  polypeptides  protein Bonding (ionic & H) can create asymmetrical attractions

  16. Chaperoninsassist in proper folding of proteins

  17. Protein structure and function are sensitive to chemical and physical conditions • Unfolds or denaturesif pHand temperature are not optimal

  18. change in structure = change in function

  19. II. Nucleic Acids Function: store hereditary info

  20. Nucleotides: monomer of DNA/RNA Nucleotide = Sugar + Phosphate + Nitrogen Base

  21. Nucleotide phosphate A – T G – C Nitrogen base 5-C sugar

  22. Information flow in a cell:DNA  RNA  protein

  23. III. Carbohydrates • Fueland building material • Include simple sugars (fructose) and polymers (starch) • Ratio of 1 carbon: 2 hydrogen: 1 oxygen or CH2O • monosaccharide  disaccharide  polysaccharide • Monosaccharides = monomers (eg. glucose, ribose) • Polysaccharides: • Storage (plants-starch, animals-glycogen) • Structure (plant-cellulose, arthropod-chitin) Differ in position & orientation of glycosidic linkage

  24. The structure and classification of some monosaccharides

  25. Linear and ring forms of glucose

  26. Carbohydrate synthesis

  27. Cellulose vs. Starch Two Forms of Glucose:  glucose &  glucose

  28. Cellulose vs. Starch • Starch =  glucose monomers • Cellulose =  glucose monomers

  29. Storage polysaccharides of plants (starch) and animals (glycogen)

  30. Structural polysaccharides: cellulose & chitin (exoskeleton)

  31. IV. Lipids • Fats (triglyceride): store energy • Glycerol + 3 Fatty Acids • saturated, unsaturated, polyunsaturated • Steroids:cholesterol and hormones • Phospholipids:lipid bilayer of cell membrane • hydrophilic head, hydrophobic tails Hydrophilic head Hydrophobic tail

  32. Cholesterol, a steroid

  33. The structure of a phospholipid

  34. Hydrophobic/hydrophilic interactions make a phospholipid bilayer

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