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Macromolecules Lecture


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Macromolecules Lecture

  1. 1. CHAPTER 5 The Structure and Function of Macromolecules <ul><li>“ You are what you eat!” </li></ul>
  2. 2. What does it mean to be a MACROmolecule? <ul><li>You must be a Large molecule </li></ul><ul><li>You have a complex structure </li></ul>“ little” molecule Macromolecule
  3. 3. I. Most macromolecules are polymers, built from monomers <ul><li>What is a polymer? </li></ul><ul><ul><li>Poly = many; mer = part. </li></ul></ul><ul><ul><li>A long molecule made of monomers bonded together </li></ul></ul><ul><li>What is a monomer? </li></ul><ul><ul><li>A monomer is a sub-unit of a polymer. </li></ul></ul>
  4. 4. <ul><li>Three of the classes of life’s organic molecules are polymers </li></ul><ul><ul><li>Carbohydrates, Proteins, Nucleic acids </li></ul></ul>
  5. 5. A. Making and Breaking Polymers <ul><li>How do monomers bind to form polymers? </li></ul><ul><ul><li>condensation reactions called dehydration synthesis (removal of water) </li></ul></ul>
  6. 6. How can polymers break down when monomers are needed? <ul><li>Hydrolysis reaction </li></ul><ul><ul><li>Hydro = water; lysis = break </li></ul></ul><ul><ul><li>Water is added and the lysis of the polymer occurs. </li></ul></ul>
  7. 7. Hydrolysis
  8. 8. II. Classes of Organic Molecules: <ul><ul><li>Carbohydrates </li></ul></ul><ul><ul><li>Lipids </li></ul></ul><ul><ul><li>Proteins </li></ul></ul><ul><ul><li>Nucleic Acids </li></ul></ul>
  10. 10. <ul><li>What are Carbohydrates? </li></ul><ul><ul><li>Sugars and their polymers </li></ul></ul><ul><ul><li>Carbo = carbon, hydrate = water; carbohydrates have the molecular formula (CH 2 O) n </li></ul></ul><ul><li>Functions of Carbohydrates in living things: </li></ul><ul><ul><li>Major fuel/energy source </li></ul></ul><ul><ul><li>Can be used as raw materials for other Macromolecules </li></ul></ul><ul><ul><li>Complex sugars = building material in plants </li></ul></ul><ul><li>What is the Carbohydrate Monomer? </li></ul><ul><ul><li>Monosaccharide (“mono” = one; “saccharide” = sugar) </li></ul></ul>
  11. 11. 1. Structure of Monosaccharides <ul><li>Contain only C, H, O </li></ul><ul><li>Hydroxyl group is attached to each carbon </li></ul><ul><li>One carbon contains a carbonyl group </li></ul>
  12. 12. <ul><li>Classified according to the size of their carbon chains and location of Carbonyl group </li></ul>
  13. 13. <ul><li>In aqueous solutions many monosaccharides form rings: </li></ul>
  14. 14. 2. Structure of Disaccharides <ul><li>Consist of two monosaccharides </li></ul><ul><li>Are joined by a glycosidic linkage </li></ul><ul><li>What reaction forms the glycosidic linkage? </li></ul><ul><ul><li>Dehydration synthesis </li></ul></ul>
  15. 16. 3. Polysaccharides <ul><li>Structure : Polymers of a few hundred or a few thousand monosaccharides. </li></ul><ul><li>Functions : energy storage molecules or for structural support: </li></ul>
  16. 18. <ul><li>Starch is a plant storage form of energy, easily hydrolyzed to glucose units </li></ul>
  17. 19. <ul><li>Cellulose is a fiber-like structural material made of glucose monomers used in plant cell walls </li></ul>
  18. 20. Why is Cellulose so strong? <ul><li>Glucose monomers are flipped to expose equal Hydroxyl groups on either side of the chain </li></ul><ul><li>When Cellulose chains are lined up next to each other, they Hydrogen Bond making a strong material that’s difficult to break! </li></ul>
  19. 22. <ul><li>Glycogen is the animal short-term storage form of energy </li></ul><ul><li>Glucose monomers </li></ul>
  20. 23. <ul><li>Chitin is a polysaccharide used as a structural material in arthropod exoskeleton and fungal cell walls. </li></ul>
  21. 24. B. LIPIDS <ul><li>What are Lipids? </li></ul><ul><li>Fats, phospholipids, steroids, waxes, pigments </li></ul><ul><li>Hydrophobic (“hydro”=water; “phobic” = fearing) </li></ul><ul><li>Consist mostly of hydrocarbons </li></ul><ul><li>Do NOT consist of polymers </li></ul>
  22. 25. <ul><li>Functions of Lipids in living things: </li></ul><ul><ul><li>Energy storage </li></ul></ul><ul><ul><li>membrane structure </li></ul></ul><ul><ul><li>Protecting against desiccation (drying out). </li></ul></ul><ul><ul><li>Insulating against cold. </li></ul></ul><ul><ul><li>Absorbing shocks. </li></ul></ul><ul><ul><li>Regulating cell activities by hormone actions. </li></ul></ul>
  23. 26. 1. Structure of Fats (Triglycerides) <ul><li>Consist of a single glycerol and usually three fatty acids </li></ul><ul><li>Glycerol – an alcohol with three carbons </li></ul><ul><li>Fatty Acid - Long Hydrocarbon chains with a Carboxyl group at one end. </li></ul>
  24. 28. Saturated and Unsaturated Fats <ul><li>Unsaturated fats : </li></ul><ul><ul><li>one or more double bonds between carbons in the fatty acids allows for “kinks” in the tails </li></ul></ul><ul><ul><li>liquid at room temp </li></ul></ul><ul><ul><li>most plant fats </li></ul></ul><ul><li>Saturated fats: </li></ul><ul><ul><li>No double bonds in fatty acid tails </li></ul></ul><ul><ul><li>solid at room temp </li></ul></ul><ul><ul><li>most animal fats </li></ul></ul>(a) Saturated fat and fatty acid Stearic acid (b) Unsaturated fat and fatty acid cis double bond causes bending Oleic acid
  25. 30. Saturated fatty acid
  26. 31. Saturated fatty acid Unsaturated fatty acid Why are Unsaturated Fats better for you than Saturated Fats?
  27. 32. 3. Phospholipids <ul><li>Structure : Glycerol + 2 fatty acids + phosphate group. </li></ul><ul><li>Function : Main structural component of membranes, where they arrange in bilayers. </li></ul>
  28. 33. Phospholipids in Water
  29. 34. 4. Waxes <ul><li>Function: </li></ul><ul><ul><li>Lipids that serve as coatings for plant parts and as animal coverings. </li></ul></ul>
  30. 35. 5. Steroids <ul><li>Structure : Four carbon rings with no fatty acid tails </li></ul><ul><li>Functions : </li></ul><ul><ul><li>Component of animal cell membranes (Ex: Cholesterol) </li></ul></ul><ul><ul><li>Modified to form sex hormones </li></ul></ul>
  31. 36. PROTEINS
  32. 37. C. Proteins <ul><li>What are Proteins? </li></ul><ul><ul><li>Chains of amino acid monomers connected by peptide bonds </li></ul></ul><ul><ul><li>Have a 3 dimensional globular shape </li></ul></ul>
  33. 38. Examples of Protein Functions <ul><li>Immune System </li></ul><ul><ul><li>Binding of antibodies (proteins) to foreign substances </li></ul></ul><ul><li>Transport </li></ul><ul><ul><li>Membrane transport proteins that move substances across cell membranes </li></ul></ul><ul><ul><li>Hemoglobin carries oxygen, iron, and other substances through the body. </li></ul></ul><ul><li>Muscle Contraction </li></ul><ul><ul><li>actin and myosin fibers that interact in muscle tissue. </li></ul></ul><ul><li>Signaling </li></ul><ul><ul><li>Hormones such as insulin regulate sugar levels in blood. </li></ul></ul>
  34. 40. Amino Acids <ul><li>Monomers of polypeptides </li></ul><ul><ul><li>Molecules with carboxyl and amino groups </li></ul></ul><ul><ul><li>Differ in their properties due to differing side chains, called R groups </li></ul></ul>
  35. 41. 20 different amino acids exist The sequence of amino acids and the interactions of the different amino acids determine a proteins shape
  36. 42. <ul><li>Peptide bonds connect amino acids to form polypeptide chains </li></ul><ul><li>One or more polypeptide chains make up a protein </li></ul>
  37. 43. Proteins are very complex! Their specific structure determines their function. HEMOGLOBIN: Transport of gases and iron in blood ACTIN: Filament involved in muscle contraction
  38. 44. Four Levels of Protein Structure <ul><li>Primary structure </li></ul><ul><ul><li>Is the unique sequence of amino acids in a polypeptide </li></ul></ul>Figure 5.20 – Amino acid subunits + H 3 N Amino end o Carboxyl end o c Gly Pro Thr Gly Thr Gly Glu Seu Lys Cys Pro Leu Met Val Lys Val Leu Asp Ala Val Arg Gly Ser Pro Ala Gly lle Ser Pro Phe His Glu His Ala Glu Val Val Phe Thr Ala Asn Asp Ser Gly Pro Arg Arg Tyr Thr lle Ala Ala Leu Leu Ser Pro Tyr Ser Tyr Ser Thr Thr Ala Val Val Thr Asn Pro Lys Glu Thr Lys Ser Tyr Trp Lys Ala Leu Glu Lle Asp
  39. 45. <ul><li>Secondary structure </li></ul><ul><ul><li>Is the folding or coiling of the polypeptide into a repeating configuration resulting from hydrogen bonding of amino with carboxyl groups </li></ul></ul><ul><ul><li>Includes the α helix and the β pleated sheet </li></ul></ul>O C α helix β pleated sheet Amino acid subunits N C H C O C N H C O H R C N H C O H C R N H H R C O R C H N H C O H N C O R C H N H H C R C O C O C N H H R C C O N H H C R C O N H R C H C O N H H C R C O N H R C H C O N H H C R C O N H H C R N H O O C N C R C H O C H R N H O C R C H N H O C H C R N H C C N R H O C H C R N H O C R C H H C R N H C O C N H R C H C O N H C H H Figure 5.20
  40. 46. <ul><li>Tertiary structure </li></ul><ul><ul><li>Is the overall three-dimensional shape of a polypeptide </li></ul></ul><ul><ul><li>Results from interactions between amino acids and R groups </li></ul></ul>CH 2 CH O H O C HO CH 2 CH 2 NH 3 + C - O CH 2 O CH 2 S S CH 2 CH CH 3 CH 3 H 3 C H 3 C Hydrophobic interactions and van der Waals interactions Polypeptide backbone Hydrogen bond Ionic bond CH 2 Disulfide bridge
  41. 47. <ul><li>Quaternary structure </li></ul><ul><ul><li>Is the overall protein structure that results from the aggregation of two or more polypeptide subunits </li></ul></ul>
  42. 48. <ul><li>Chaperonins </li></ul><ul><ul><li>Are protein molecules that assist in the proper folding of other proteins </li></ul></ul>Hollow cylinder Cap Chaperonin (fully assembled) Steps of Chaperonin Action: An unfolded poly- peptide enters the cylinder from one end. The cap attaches, causing the cylinder to change shape in such a way that it creates a hydrophilic environment for the folding of the polypeptide. The cap comes off, and the properly folded protein is released. Correctly folded protein Polypeptide 2 1 3 Figure 5.23
  43. 50. Sickle Cell Disease: A simple change in Primary Structure
  44. 51. Enzymes <ul><li>Are a type of protein that acts as a catalyst, speeding up chemical reactions up to 10 billion times faster than they would spontaneously occur. </li></ul>
  45. 52. Environmental Factors That Determine Protein Conformation <ul><li>Change in environment may lead to denaturation of protein (pH, temperature, salinity, etc.) </li></ul><ul><li>Denatured protein is biologically inactive </li></ul><ul><li>Can renature if primary structure is not lost </li></ul>
  47. 54. D. Nucleic Acids : The stuff of Genes <ul><li>Nucleic acids store and transmit hereditary information </li></ul><ul><li>Genes </li></ul><ul><ul><li>Are the units of inheritance </li></ul></ul><ul><ul><li>Program the amino acid sequence of polypeptides </li></ul></ul><ul><ul><li>Are made of nucleic acids </li></ul></ul>
  48. 55. Two Kinds of Nucleic Acids <ul><li>DNA ( Deoxyribonucleic acid) </li></ul><ul><ul><li>double stranded </li></ul></ul><ul><ul><li>can self replicate </li></ul></ul><ul><ul><li>makes up genes which code for proteins is passed from one generation to another </li></ul></ul><ul><li>RNA ( Ribonucleic acid) </li></ul><ul><ul><li>single stranded </li></ul></ul><ul><ul><li>functions in actual synthesis of proteins coded for by DNA </li></ul></ul><ul><ul><li>is made from the DNA template molecule </li></ul></ul>
  49. 57. 1. Nucleotide Monomer Structure <ul><li>Both DNA and RNA are composed of nucleotide monomers. </li></ul><ul><li>Nucleotide = 5 carbon sugar, phosphate, and nitrogenous base </li></ul>Deoxyribose in DNA Ribose in RNA
  50. 59. 2. Building the Polymer <ul><li>Phosphate group of one nucleotide forms strong covalent bond with the #3 carbon of the sugar of the other nucleotide. </li></ul>
  51. 60. <ul><li>DNA: </li></ul><ul><li>Double helix </li></ul><ul><li>2 polynucleotide chains wound into the double helix </li></ul><ul><li>Base pairing between chains with H bonds </li></ul><ul><li>A - T </li></ul><ul><li>C - G </li></ul>
  52. 61. Summary of the Organic Molecules: