1. 1 Chemicals of life

2. 2015/9/9 2

3. The Macromolecules of cells

4. 2015/9/9 4 The Unique Water molecule

5. The water molecule is not linear 5 V-shaped linear

6. Polarity and hydrogen bond 6

7. 7

8. 8

9. Result of regular arrangement of water molecules: ice crystals 9

10. 10 Peculiar Properties of water A waterstrider / pond skater demonstrates how cohesion (H-bonds) between water molecules allow it to move across water's surface. 1.Universal Solvent 2.High heat capacity, heat of fusion, heat of vaporizaton 3. Density & Freezing properties 4. Surface tension

11. 11

12. Water- an universal solvent ----- for polar and charged particles

13. 13 Water and oil are immiscible. “like dissolves like” oil (long hydrocarbon chain, non-polar) Vs water (polar, H-bonding)

14. 14 Fatty substances form membrane compartments in cells to allow different reactions to take place independently of one another

15. 15 High heat capacity, high heat of vaporization and fusion

16. 16 High heat capacity, high heat of vaporization and fusion

17. 17 high heat of vaporization

18. 18

19. 19 Cohesion in water molecule

20. 20 Cohesion and surface tension

21. 21 Cohesion and water transport in plants

22. 22 Ice is less dense than water

23. 23

24. 24 What would happen to life in the lake when the lake is frozen?

25. 25 Water as a reactant photosynthesis digestion

26. Turgor and wilting  Turgor loss in plants causes wilting  Which can be reversed when the plant is watered

27. 27 Water- the habitat for many life forms

28. 28 Minerals in DNA – P, N,

29. 29 Minerals in functional molecules – haemoglobin, chlorophyll

30. 2015/9/9 30 Minerals : Iron containing haem in haemoglobin holds oxygen

31. 31 Minerals - calcium

32. 32 Minerals- nerve activities: ions movements _ Na+, K+

33. 2015/9/9 33 Carbohydrates Monosaccharides with different no. of Carbon

34. 2015/9/9 34 Common Monosaccharides Six-carbon sugars

35. Linear and Ring forms 35

36. 36 Alpha and beta form of glucose

37. Interconversion of Mono-- Di-- polysaccharides 37

38. Condensation / dehydration synthesis 38

39. 2015/9/9 39 Disaccharides

40. Reducing and non-reducing sugars 40

41. Test for reducing sugars 41

42. 42 Sugars are sweet! How sweet is it? Sugar Relative sweetness to sucrose lactose0.16 galactose0.32 maltose0.33 sucrose1.0 fructose1.73 aspartame180 saccharin450

43. Polysaccharide-starch 43

44. 44 helical structure of starch

45. Starch grains in plant cells 45

46. Mitochondria Glycogen granules 0.5 µm Glycogen Glycogen: an animal polysaccharide

47. 47 Cellulose- a structural material

48. LE 5-7 a Glucose a and b glucose ring structures b Glucose Starch: 1–4 linkage of a glucose monomers. Cellulose: 1–4 linkage of b glucose monomers.

49. Polymers with alpha glucose are helical Polymers with beta glucose are straight In straight structures, H atoms on one strand can bond with OH groups on other strands Parallel cellulose molecules held together this way are grouped into microfibrils, which form strong building materials for plants

50. LE 5-8 Cellulose molecules Cellulose microfibrils in a plant cell wall Cell walls Microfibril Plant cells 0.5 µm  Glucose monomer

51.  Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulose  Cellulose in human food passes undigested through the digestive tract as insoluble fiber  Some microbes use enzymes to digest cellulose  Many herbivores, from cows to termites, have symbiotic relationships with these microbes

54.  Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods e.g insects  Chitin also provides structural support for the cell walls of many fungi  Chitin can be used as surgical thread

55. 55 Obesity

56. What are Lipids? 56  The unifying feature of lipids is having little or no affinity for water  Lipids are hydrophobic -- because  they consist mostly of hydrocarbons, which form nonpolar covalent bonds  The most biologically important lipids are fats, phospholipids, and steroids

57. LE 5-11a Dehydration reaction in the synthesis of a fat Glycerol Fatty acid (palmitic acid)

58. 58 A Triglyceride

59.  Fats made from saturated fatty acids are called saturated fats  Most animal fats are saturated  Saturated fats are solid at room temperature  A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits

60. LE 5-12a Saturated fat and fatty acid. Stearic acid

61. Saturated and unsaturated fats 61

62.  Fats made from unsaturated fatty acids are called unsaturated fats  Plant fats and fish fats are usually unsaturated  Plant fats and fish fats are liquid at room temperature and are called oils

63. LE 5-12b Unsaturated fat and fatty acid. Oleic acid double bond causes bending

64. 2015/9/9 64

65. 65 Phospholipid -replacing a fatty acid (nonpolar) with a phosphate (polar)

66. Phospholipids- lipids with a polar head 66

67. Lipid bilayer 67

68. Lipid bilayer forms membrane

69. 2015/9/9 69

70.  The basic structure of testosterone (male hormone; 睪固酮 ) and estradiol (female hormone; 雌激素 ) is identical.  Both are steroids with four fused carbon rings, but they differ in the functional groups attached to the rings.  These then interact with different targets in the body.

71. Steroid tree 71

72. Proteins have many structures, resulting in a wide range of functions

73.  Proteins account for more than 50% of the dry mass of most cells  Protein functions include support, storage, transport, cellular communications, movement, body defense

75. 75 Amino acids – general formula Variable properties according to the R group

76. Amino acids - examples 76

77. Peptide bond - dipeptide 77

78. Amino Acid Polymers  Amino acids are linked by peptide bonds  A polypeptide is a polymer of amino acids  Polypeptides range in length from a few monomers to more than a thousand  Each polypeptide has a unique linear sequence of amino acids

79. Polypeptides  Polypeptides are polymers of amino acids  A protein consists of one or more polypeptides

80. Protein Conformation and Function  A functional protein consists of one or more polypeptides folded, and coiled into a unique shape  The sequence of amino acids determines a protein’s three-dimensional conformation  A protein’s conformation determines its function

81. A ribbon model Groove A space-filling model

82. Four Levels of Protein Structure  The primary structure of a protein is its unique sequence of amino acids  Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain  Tertiary structure is determined by interactions among various side chains (R groups)  Quaternary structure results when a protein consists of multiple polypeptide chains

83.  Primary structure, the sequence of amino acids in a protein, is like the order of letters in a long word  Primary structure is determined by inherited genetic information

84.  Typical secondary structures are a coil called a helix and a folded sheet structure Amino acid subunits  helix  pleated sheet

85.  Tertiary structure is determined by interactions between R groups, rather than interactions between backbone constituents  These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions  Strong covalent bonds called disulfide bridges may reinforce the protein’s conformation

86. Hydrophobic interactions and van der Waals interactions Polypeptide backbone Disulfide bridge Ionic bond Hydrogen bond

87.  Quaternary structure results when two or more polypeptide chains form one macromolecule  Collagen is a fibrous protein consisting of three polypeptides coiled like a rope  Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains

88.  Chains  Chains Hemoglobin Iron Heme Collagen Polypeptide chain Polypeptide chain

89. Sickle-Cell Disease: A Simple Change in Primary Structure  A slight change in primary structure can affect a protein’s conformation and ability to function  Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin

90. LE 5-21a Red blood cell shape Normal cells are full of individual hemoglobin molecules, each carrying oxygen. 10 µm Red blood cell shape Fibers of abnormal hemoglobin deform cell into sickle shape.

91. LE 5-21b Primary structure Secondary and tertiary structures 1 2 3 Normal hemoglobin Val His Leu 4 Thr 5 Pro 6 Glu 7 Primary structure Secondary and tertiary structures 1 2 3 Sickle-cell hemoglobin Val His Leu 4 Thr 5 Pro 6 ValGlu 7 Quaternary structure Normal hemoglobin (top view)         Function Molecules do not associate with one another; each carries oxygen. Quaternary structure Sickle-cell hemoglobin Function Molecules interact with one another to crystallize into a fiber; capacity to carry oxygen is greatly reduced. Exposed hydrophobic region  subunit

92. What Determines Protein Conformation?  In addition to primary structure, physical and chemical conditions can affect conformation  Alternations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel  This loss of a protein’s native conformation is called denaturation  A denatured protein is biologically inactive

93. Protein – internal Forces/ bonding 93

94. LE 5-22 Denaturation Renaturation Denatured proteinNormal protein

95. Protein – What level of protein structure is represented below? 95

96. 2015/9/9 96 Protein – Levels of complexity

97. Protein – globular proteins proteins with physiological function 97

98. Globular protein e.g. enzyme

99. Protein – globular proteins: e.g. antibodies 99

100. Structural proteins

101. Protein – Fibrous proteins with structural function e.g. collagen 101