biological-molecules.pptx biological molecules

Ideas about the structure of the atom have changed over the years. The Bohr theory thought of it as a small nucleus of protons and neutrons surrounded by circulating electrons.
Each shell or energy level could hold a maximum number of electrons.
The energy of levels became greater as they got further from the nucleus and electrons filled energy levels in order.

The theory couldn’t explain certain aspects of chemistry.

1. Biological Molecules Objectives : Describe the structure of the molecules that make up living organisms The chemicals found in living organisms What elements are you made of? Which 3 elements are most common in your body? You should know the answer to this!

2. Carbon Based Life Organic molecules contain carbon Carbon can bond with itself So it can make chains of varying lengths to form a backbone to which other atoms can bind This produces a large variety of shaped and sized molecules.

3. How do these elements form compounds? ( eg sugar)

4. Forming Molecules Covalent bond : shared electrons, forms molecules, very strong Ionic bond : opposite charges attract between ions, weaker than covalent Hydrogen Bonds : hydrostatic forces formed between uneven charges in polar molecules. Weak individually, but may collectively alter the properties of molecules.

5. Monomers Polymer Polymerisation Monomer Polymer Amino acid Polypeptide / Protein Nucleotide Poly-nucleotide (DNA) Monosaccharide (sugar) Polysaccharide ( eg starch)

6. Hydrolysis

7. Condensation

8. Condensation Hydrolysis When monomers bind together a water molecule is formed When polymers break down water is added to break the bonds

9. Metabolism All the chemical processes in the body ( eg breaking down and formation of molecules)

10. Molar Solution? Hydrochloric Acid HCl 1M

11. Mole Formula mass in grams 1 mole of carbon = 12g 1 mole of oxygen = 16g 1 mole of water = 18g It is the mass of 6 x 10 23 atoms ( Avagadro’s number)

12. Molar solution 1 mole of a chemical in 1 litre of water How many grams of NaCl would you dissolve in a litre of water to make a 1M solution? How many grams of HCl would be in 2 litres of 1M solution? How much H 2 SO 4 would be in 1 litre of 0.5 M solution? A) If you had a 1M solution of NaOH and you wanted a 0.5M solution what would you do? 4. B) What exact volumes would you use if you wanted to make 100 cm 3 of this NaCl

13. Carbohydrates Objectives: Compare monosaccharides and disaccharides Describe how to test for reducing and non-reducing sugars Sugars Starter : similarities and differences

14. Carbo hydr ates carbon hydrogen oxygen Monomer = sugar “saccharide” monosaccharide disaccharide polysaccharide sugars

15. Monosaccharides Sweet Soluble (CH 2 O) n Glucose, galactose, fructose

16. Isomers of Glucose Same formula (C 6 H 12 O 6 ) Different structure

17. Disaccharides 2 monosaccharides bonded together Joined by condensation reaction The bond that joins them is a glycosidic bond Glucose Glucose Glucose Glucose H 2 O Maltose Glycosidic bond

18. Condensation

19. Hydrolysis

20. Testing for reducing sugars Use Benedict’s reagent

21. Testing for non-reducing sugars Hydrolyse with acid Neutralise Use B endict’s reagent

22. Polysaccharides Describe how starch, cellulose and glycogen form Describe the test for starch Objectives Starter quiz: What type of reaction bonds monosaccharides together? What disaccharide is formed from glucose and fructose? Maltose is a disaccharide made up of two glucose (C 6 H 12 O 6 ) monomers. What is the chemical formula of maltose? A student tested a biscuit by adding Benedict’s reagent and heating for 2 minutes. The test was negative. What can he conclude about the biscuit? What further test should he do to improve his conclusion?

23. Starter quiz: What type of reaction bonds monosaccharides together? What disaccharide is formed from glucose and fructose? Maltose is a disaccharide made up of two glucose (C 6 H 12 O 6 ) monomers. What is the chemical formula of maltose? A student tested a biscuit by adding Benedict’s reagent and heating for 2 minutes. The test was negative. What can he conclude about the biscuit? What further test should he do to improve his conclusion? condensation Sucrose C 12 H 22 O 11 Does not contain reducing sugars Test for non-reducing sugar: Heat with HCl , neutralise, add Benedict’s

24. Polysaccharides Many monosaccharides joined together Glycosidic bonds join all the monosaccharides All formed by condensation reactions Large molecules Insoluble (good for storage) Starch, cellulose, glycogen

25. Polysaccharide Monomer Structure Property Where found Starch Glycogen Cellulose

26. ( α glucose) ( α glucose) ( β glucose)

27. Starch Polysaccharide made of chains of α glucose

28. Glycosidic bond

29. Starch Polysaccharide made of chains of α glucose The unbranched chain is wound into a tight coil – giving it a compact shape

30. Starch 1. Found in plant cells as small grains: Storage molecule (stores glucose for respiration) Found mainly in seeds and storage organs ( eg potato tubers) 2. Not found in animal cells – but is the main source of energy in our diet Function:

31. Starch Why is starch such a good storage molecule? 1. It is insoluble so it will : not affect osmosis ( eg will not draw water into a cell when starch levels are high) not diffuse out of a cell 2. It is compact so a lot can be stored in a small place 3. It is hydrolysed to form α glucose – a molecule that is easily transported and readily used in respiration

32. Glycogen Similar structure to starch ( α glucose) Shorter than starch More branched than starch

33. Glycogen Function: Carbohydrate storage in animals Stored as small granules in animal cells Mainly found in muscles and the liver Found only in animal cells – never in plant cells

34. Glycogen Why is glycogen a good storage molecule? All the same reasons as starch: Insoluble 2. Compact 3. E asily hydrolysed Plus the shorter chains make it even more readily hydrolysed

35. Cellulose Polysaccharide chain made of β glucose

36. Alpha glucose Beta glucose H H H H H OH OH OH CH 2 OH O OH H H H H H OH OH OH CH 2 OH O OH

37. Alpha glucose Beta glucose H H H H H OH OH OH CH 2 OH O OH H H H H H OH OH OH CH 2 OH O OH

38. Cellulose Polysaccharide chain made of β glucose The CH 2 OH groups alternate above and below the chain

39. Uncoiled, unbranched chains are formed – running parallel to each other Weak hydrogen bonds form cross-links between parallel chains The large number of H bonds make this a very strong material Cellulose

40. Cellulose Microfibrils Cellulose molecules are grouped together into microfibrils

41. Cellulose Microfibrils Cellulose molecules are grouped together into microfibrils These are arranged in parallel groups: “fibres”

42. Cellulose Function Major component of plant cell wall Adds rigidity Prevents bursting by exerting inwards pressure on cell This allows cells to become turgid Providing support and structure to produce maximum surface area for photosynthesis to take place

43. Polysaccharide Monomer Structure Property Where found Starch α glucose Coiled chain Branched or unbranched . Branched form has many ends – so easy to release glucose Compact: stored in small space Insoluble – does not affect water potential, does not diffuse Hydrolysed into glucose: respiration Grains in plant cells, seeds, storage organs. Human diet! Glycogen α glucose Coiled chain Similar, but shorter than starch More branches – easier to release glucose (animals need more energy than plants as they are more active!) Insoluble – does not affect water potential, does not diffuse Hydrolysed into glucose: respiration Storage in a nimals, bacteria. Cellulose β glucose Straight, unbranched chains, running parallel to each other Many H bonds between chains: strong Microfibrils run in parallel groups to form fibres Rigid – stops cells bursting and allows plant cells to become turgid = maximum are for photosynthesis Plant cell walls

44. Testing for Starch Add iodine (brown / orange colour) Blue / black = positive result, starch present No change = negative result, no starch present

45. Sucrose Maltose Glycogen Cellulose Made only from glucose molecules joined together Branched molecule Soluble in water 3 Marks (AQA, 2007)

46. Sucrose Maltose Glycogen Cellulose Made only from glucose molecules joined together Branched molecule Soluble in water 3 Marks (AQA, 2007)

47. Sucrose Maltose Glycogen Cellulose Made only from glucose molecules joined together x    Branched molecule x x  x Soluble in water   x x 3 Marks (AQA, 2007)

48. Lipids Objective Link the structure of lipids to their function Describe how to test for lipids What are lipids like?

49. Lipids Carbon, hydrogen and oxygen (lower ratio of oxygen than in carbs ) Insoluble in water Most common lipids: triglycerides , phospholipids and waxes Fats are solid (at R.T.) Oils are liquid Not polymers like starch and protein Soluble in alcohol and acetone

50. Why do we need lipids?

51. Why do we need lipids? Plasma membranes (phospholipids and cholesterol)

52. Why do we need lipids? Plasma membranes energy 35% of our energy (11% saturated)

53. Why do we need lipids? Plasma membranes energy protection

54. Why do we need lipids? Plasma membranes energy protection hormones

55. Why do we need lipids? Plasma membranes energy protection hormones Insulation

56. Why do we need lipids? Plasma membranes energy protection hormones Insulation Waterproofing

57. Triglycerides Glycerol Fatty acid Fatty acid Fatty acid Triglycerides (main type of fat we eat)

58. Triglycerides Glycerol Fatty acid Fatty acid Fatty acid There are many different types of fatty acid , but all have COOH (carboxyl group)

59. Triglycerides (main type of fat we eat) Made of glycerol and 3 fatty acids

60. Triglycerides (main type of fat we eat) Made of glycerol and 3 fatty acids Glycerol CH 2 OH CH 2 OH CH 2 OH

61. Glycerol Triglycerides (main type of fat we eat) Fatty acid Fatty acid Fatty acid CH 2 OH CH 2 OH CH 2 OH HOOC HOOC HOOC

62. Triglycerides (main type of fat we eat) Made of glycerol and 3 fatty acids Glycerol CH 2 OH CH 2 OH CH 2 OH Fatty acid Fatty acid Fatty acid HOOC HOOC HOOC Draw the a diagram to represent the reaction that occurs to create a triglyceride

63. Triglycerides Glycerol Fatty acid Fatty acid Fatty acid

64. + 3H 2 O Triglyceride CONDENSATION

65. Glycerol Triglycerides Fatty acid Fatty acid Fatty acid CH 2 OH CH 2 OH CH 2 OH HOOC HOOC HOOC

66. Glycerol Triglycerides Fatty acid Fatty acid Fatty acid CH 2 OH CH 2 OH CH 2 OH HOOC HOOC HOOC

67. Glycerol Triglycerides Fatty acid Fatty acid Fatty acid CH 2 O CH 2 O CH 2 O OC OC OC

68. Glycerol Triglycerides Fatty acid Fatty acid Fatty acid CH 2 O CH 2 O CH 2 O OC OC OC

69. Glycerol Triglycerides Fatty acid Fatty acid Fatty acid CH 2 O CH 2 O CH 2 O OC OC OC

70. Glycerol Triglycerides Fatty acid Fatty acid Fatty acid CH 2 O CH 2 O CH 2 O OC OC OC Triglyceride Fatty acids bind to glycerol with ester bonds

71. + 3H 2 O Triglyceride Fatty acids bind to glycerol with ester bonds

72. Saturated or Unsaturated?

73. Fatty acids can be saturated or unsaturated

74. Saturates Unsaturates Monounsaturates Polyunsaturates

75. Saturates Unsaturates Monounsaturates Polyunsaturates No double bonds – so more H per C Double bonds – so less H per C 1 double bond More than 1 double bond The more unsaturated the fat is the more liquid it is Animal fats are high in …………. Plant fats are high in …………

76. Relating Structure and Function High ratio of energy Low mass:energy ratio Insoluble Release water when broken down Explain how these properties help fat perform its function

77. Phospholipids

78. Phospholipids Like the triglyceride – but 1 fatty acid is replaced with a phosphate molecule.

79. Phospholipids Like the triglyceride – but 1 fatty acid is replaced with a phosphate molecule. Glycerol Fatty acid Fatty acid CH 2 O CH 2 O CH 2 OC OC Phosphate

80. Phospholipids Simplified diagram:

81. Phospholipids Simplified diagram: Hydrophilic Hydrophobic

82. Phospholipids Simplified diagram: Hydrophilic Hydrophobic “Water loving” “Water hating”

83. Phospholipids Simplified diagram: Hydrophilic Hydrophobic “Water loving” “Water hating” Phospholipids are polar

84. If you mixed phospholipids with water what would happen? Water

85. Water If you mixed phospholipids with water what would happen?

86. Water If you mixed phospholipids with water what would happen? Monolayer

87. If you mixed phospholipids with water what would happen?

88. If you mixed phospholipids with water what would happen? Bilayer

89. Test for Lipids Grind or finely chop food sample Add about 1cm depth to a test tube (for olive oil just add 2 drops) Add 3cm 3 ethanol Put bung on test tube Shake at least 10 times to dissolve the lipids in the ethanol Allow to settle Add 3 cm depth of distilled water Result: white emulsion floating near top of water = lipids present no white emulsion = no lipids (or level of lipids belwo sensitivity of the test)