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CHAPTER 5

CHAPTER 5. The Structure and Function of Macromolecules. KEY CONCEPTS. Focus on how STRUCTURE and biochemical properties relate to FUNCTION Focus on how building block MONOMERS are bonded together by specific LINKAGES. KEY CONCEPTS. Common SYNTHESIS and BREAKDOWN reactions

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CHAPTER 5

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  1. CHAPTER 5 The Structure and Function of Macromolecules

  2. KEY CONCEPTS • Focus on how STRUCTURE and biochemical properties relate to FUNCTION • Focus on how building block MONOMERS are bonded together by specific LINKAGES

  3. KEY CONCEPTS • Common SYNTHESIS and BREAKDOWN reactions • Macromolecules are POLYMERS • MER - units TRI - three • POLY - many DI - two • OLIGO - several MONO - one

  4. POLYMERS monomer + monomer + monomer + monomer = a big ‘ol polymer Unity within diversity the same monomers are common to all forms of life

  5. How to make a Macromolecule DEHYDRATION SYNTHESIS - bonding of small subunits to form a larger end product by removing water.

  6. Figure 5.2 The synthesis and breakdown of polymers

  7. How to breakdown a macromolecule… HYDROLYSIS - digestion or degradation of large polymers by the addition of water

  8. Main Classes Of Macromolecules • CARBOHYDRATES • LIPIDS • PROTEINS • NUCLEIC ACIDS

  9. Carbohydrates • Sugars • end in -ose • aldehydes & ketones • Isomer City • General formula: • C H2 O

  10. CARBOHYDRATES • MONOSACCHARIDES examples: • glucose C6 hexose • ribose C5 pentose • glyceraldehyde C3 triose

  11. Identify the carbons Linear vs. ring structure ?????

  12. DISACCHARIDES

  13. DISACCHARIDES • Monosaccharide monomers • Dehydration synthesis • Glycosidic linkages • 1-4 glycosidic linkage (maltose) • 1-2 glycosidic linkage (sucrose) • BIOFUNCTION: transport of fuel

  14. CARBOHYDRATES • POLYSACCHARIDES (100’S --> 1000’S) Storage STARCH (plants) 1-4 linkage, unbranched helix GLYCOGEN (animals) 1-6 linkage, branching helix

  15. Figure 5.6 Storage polysaccharides

  16. Molecular Shape

  17. CARBOHYDRATES • MORE POLYSACCHARIDES Structural CELLULOSE - plant cell walls • most abundant organic molecule • linear fibrils -> rope --> composite • alpha vs. beta glucose/digestion CHITIN - exoskeletons & cell walls - tough, insoluble

  18. Figure 5.9 Chitin, a structural polysaccharide: exoskeleton and surgical thread

  19. Figure 5.8 The arrangement of cellulose in plant cell walls

  20. CARBOHYDRATES Summary of biofunctions • Immediate fuel • Storage & transport of fuel • Structural building material

  21. Lipids A diverse group, Insoluble in water, hydrophobic, nonpolar, mostly hydrocarbon chains technically not polymers??

  22. LIPIDS • Fats or Triglycerides • glycerol + 3 fatty acids • R -COOH hydrocarbon chain 14-18 carbons + carboxyl group • ester linkage

  23. LIPIDS

  24. LIPIDS SATURATED • fully saturated w/ hydrogens • animal fats - solid at room temp. UNSATURATED • at least one double bond (kink) • plant oils -liquid at room temp. • geometric isomers (cis & trans)

  25. Figure 5.11 Examples of saturated and unsaturated fats and fatty acids 

  26. MORE LIPIDS • PHOSPHOLIPIDS • glycerol + 2 fatty acids + phosphate + charged group • hydrophilic head • hydrophobic tail • BIOFUNCTION: membranes & micelles

  27. MORE LIPIDS • STEROIDS • 4 rings + fat tail • 3 cyclohexanes + cyclopentane + hydrocarbon chain

  28. MORE LIPIDS • STEROIDS • CHOLESTEROL is modified to form steroid hormones • sex hormones + corticoids • CHOLESTEROL is also found in cell membranes

  29. CHOLESTEROL One of the most misunderstood chemicals in the human body Cho gets a BAD reputation for • Atherosclerosis • Coronary Heart Disease • Heart Attacks • Strokes • High Blood Pressure but….

  30. The Facts About Cholesterol • Precursor for steroid hormones • Precursor for bile acids • Necessary component of cell membranes Poor diet and hereditary factors predispose individuals to heart disease

  31. Proteins • “first place” • over 50% dry weight of most cells • structure fits function

  32. Fiberous Enzymes Membrane Channels Cell Recognition Hormones Transport Contraction Defense Osmotic Homeostasis Gene Regulators Proteins

  33. Check out the animations online

  34. Figure 5.1 Building models to study the structure and function of macromolecules

  35. PROTEINS • Building block monomers are amino acids • basic amino acid structure • 20 different R groups

  36. Protein: • High-molecular weight, nitrogen-containing organic compound. • Composed of one or more polypeptides. • Polypeptides are composed of amino acids. Amino Acid: Contains the following bonded to a central carbon atom. • Amino groups (NH2) • Carboxyl group (COOH) • Hydrogen atom • R group(different in each amino acid) Typically charged in the cell (-NH3+ and COO-)

  37. Fig. 6.1

  38. Fig. 6.2. Acidic and basic amino acids.

  39. Figure 5.15 The 20 amino acids of proteins: nonpolar

  40. Fig. 6.2. Neutral, non-polar (hydrophobic) amino acids.

  41. Fig. 6.2. Neutral, polar (hydrophilic) amino acids.

  42. Amino acids are joined to form unbranched polypeptides by a peptide bond. • Peptide bond = covalent bond between the carboxyl group of one amino acid and amino group of the next amino acid. Fig. 6.3 N-terminus C-terminus 5’ (DNA) 3’ (DNA)

  43. Amino Acid Summary Side Groups Determine Chemical Properties Nonpolar C-H tend to hydrophobic aggregate toward center Polar O-H, N-H are hydrophilic & tend to be found on the outside Charged acidic (-COOH) fold to outside basic (-NH3) fold to outside

  44. PROTEINS • Peptide bond formation • Amino group + carboxylic acid via dehydration synthesis • Residues • N-terminus - polypeptide chain -C-terminus

  45. PRIMARY STRUCTURE • sequence of AA’s • genetically determined • involves peptide bonds

  46. PRIMARY STRUCTURE

  47. Figure 5.20 The secondary structure of a protein

  48. TERTIARY STRUCTURE • interactions between R groups • hydrophobic interactions • ionic bonds • H-bonds • disulfide bridges between cysteine residues

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