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Understanding the Four Classes of Large Biomolecules in All Organisms

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All living organisms contain four classes of large biomolecules: lipids, polysaccharides, proteins, and nucleic acids. Each class consists of macromolecules formed from specific subunits and plays distinct roles in cellular structure, energy storage, and information processing. Lipids serve various functions, including energy storage and membrane formation. Polysaccharides are essential for information storage and structure. Proteins are polymers of amino acids and are involved in countless functions, from catalysis to defense. Nucleic acids carry genetic information critical for life.

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Understanding the Four Classes of Large Biomolecules in All Organisms

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  1. Large Biomolecules

  2. All Organisms Contain the Same Four Classes of Large Biomolecules • lipids - hydrophobic =>macromolecules - chains of subunits • polysaccharides - repetitive macromolecules =>information macromolecules • proteins • nucleic acids

  3. constituents of hydrated and dry organismsFigure 3.2

  4. All Organisms Contain the Same Four Classes of Large Biomolecules • large biomolecules consist of the same subunits in all organisms • large biomolecules are assembled, fresh from their subunits, by each organism

  5. similar reactions assemble and disassemble all classes of large biomoleculesFigure 3.3

  6. Table 3.1

  7. Four Classes of Large Biomolecules • Lipids • defined by hydrophobicity • chemically diverse hydrocarbons • several functions, e.g. • energy storage - fats & oils • cell structures - membranes • regulation - steroid & other hormones • insulation - electrical & thermal

  8. Four Classes of Large Biomolecules • Lipids • triglycerides • fats solid at 20˚C; oils liquid at 20˚C • energy per gram > carbohydrates or proteins

  9. triglyceride synthesis (esterification)Figure 3.18

  10. fats,oils, cis, transFigure 3.19 saturated unsaturated

  11. Four Classes of Large Biomolecules • membrane lipids • phospholipids • diglycerides + polar head group • amphipathic

  12. a membrane phospholipidFigure 3.20

  13. biomembrane segmentFigure 5.2

  14. amphipathic membrane phospholipidsFigure 3.21

  15. Four Classes of Large Biomolecules • other lipid classes - carotenoids (isoprenoids) • Figure 3.22 CH3 H2C = C – C = CH2 H

  16. Four Classes of Large Biomolecules • other lipid classes - steroids (isoprenoids) • Figure 3.23 CH3 H2C = C – C = CH2 H

  17. Four Classes of Large Biomolecules • other lipid classes - vitamins • Vitamin E • Vitamin K

  18. Four Classes of Large Biomolecules • other lipid classes - waxes • high molecular weight, hydrophobic compounds • useful for waterproofing p. 54

  19. Four Classes of Large Biomolecules • carbohydrates: sugars & their polymers • monosaccharides - subunits of polymers • trioses, tetroses, pentoses, hexoses, etc. • families of structural & optical isomers • aldoses; ketoses • monosaccharides ≥5 C’s occur in 3 forms • modified monosaccharides play important roles

  20. a triose and two pentosesFigure 3.14

  21. three hexosesFigure 3.14 2 aldoses and a ketose

  22. three forms of glucoseFigure 3.13 anomers ~1% ~99%

  23. modified monosaccharides and a polysaccharideFigure 3.17

  24. Four Classes of Large Biomolecules • carbohydrates: sugars & their polymers • monosaccharides - subunits of polymers • disaccharides • two monosaccharides linked by a specific glycosidic bond • differ by subunits & linked carbons

  25. two glucose-glucose disaccharidesFigure 3.15

  26. Four Classes of Large Biomolecules • carbohydrates: sugars & their polymers • monosaccharides - subunits of polymers • disaccharides • oligosaccharides • 3-20 monosaccharides linked by glycosidic bonds

  27. Four Classes of Large Biomolecules • carbohydrates: sugars & their polymers • monosaccharides - subunits of polymers • disaccharides • oligosaccharides • polysaccharides • thousands of monosaccharides linked by glycosidic bonds

  28. -1,4 polyglucoseFigure 3.16

  29. -1,4 polyglucose with -1,6 brancheFigure 3.16

  30. three forms of polyglucoseFigure 3.16

  31. Four Classes of Large Biomolecules • proteins: polymers of amino acid subunits • widely diverse functions • structure, protection, transport, defense, regulation, movement, catalysis • thousands of unique structures • some bind prosthetic groups • enzymes are chemical catalysts • functions are defined by 3-D shape

  32. Four Classes of Large Biomolecules • proteins: polymers of amino acid subunits • twenty kinds of (protein) amino acids • four levels of structure • primary - sequence of amino acids • amino (N) terminus & carboxy (C) terminus

  33. amino acids share a common structurebut have different R groups carboxylic acid amine H H2N - C - COOH R variable

  34. Amino acids organized by R groupsFigure 3.2

  35. cysteines can form disulfide bridgesFigure 3.4

  36. peptide bondsjoin the carboxyl group to theamino group long chains are called polypeptidesFigure 3.5

  37. Figure 3.6 The Four Levels of Protein Structure 1. Primary Structure: Polypeptide chain • 2. Secondary Structure: • a.  Helix • b.  Pleated sheet 3. Tertiary Structure: Polypeptides fold 4. Quaternary Structure: Polypeptides assemble into larger molecules Figure 3.6

  38. Four Classes of Large Biomolecules • proteins: polymers of amino acid subunits • tertiary & quaternary structures are stabilized by several interactions • H-bonds - between polar R groups • ionic interactions - between charged R groups • hydrophobic interactions - between non-polar R groups • disulfide bridges - between cysteines

  39. interactions that stabilize 3-D structuresFigure 3.9

  40. Four Classes of Large Biomolecules • proteins: polymers of amino acid subunits • 3-D folding is assisted by molecular chaperones • during formation • following denaturation

  41. protein denaturationFigure 3.11

  42. chaperones assist in folding polypeptidesFigure 3.12

  43. Four Classes of Large Biomolecules • nucleic acids: polymers of nucleotide subunits • DNA (deoxyribonucleic acid), & RNA (ribonucleic acid) • Store (DNA), transmit (DNA) & express (RNA) hereditary information • The Central Dogma of Molecular Biology Information Flow DNA=>RNA=>polypeptide

  44. Four Classes of Large Biomolecules • nucleic acids: polymers of nucleotide subunits • nucleotide components • pentose sugar • nitrogenous bases • purines: adenine, guanine • pyrimidines: cyosine, thymine, uracil • phosphate group O- O=P-O- O-

  45. 5-carbon sugars: pentosesFigure 3.13

  46. 5 basesFigure 3.24

  47. nucleotide componentsFigure 3.24

  48. Four Classes of Large Biomolecules • nucleic acids: polymers of nucleotide subunits • nucleotides • linked by phosphodiester bonds • sugar-phosphate backbone

  49. Figure 3.25 Distinguishing Characteristics of DNA and RNA Hydrogen bonds between purines and pyrimidines hold the two strands of DNA together. Figure 3.25

  50. DNA double helixFigure 3.27

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