Main Substances found in the Body

2. Main Substances found in the Body Water (65%) Minerals (1%) Inorganic Substances Proteins (18%) Lipids (10%) Carbohydrates (5%) Nucleic Acids (1%) Organic Substances

3. Water • Most abundant component of organisms • An excellent solvent • Reaction medium • Transport substances • Help to maintain constant body temperature • Take part in chemical reactions

4. Proteins • Most abundant organic molecules in cells • Main structural components of a cell • Serve as Enzymes & some Hormones • Provide Energy

5. Lipids (Fats & Oils) • Energy store in Plants & Animals • Important structural component of Cell Membrane • Serve as some Hormones

6. Carbohydrates • Sugars: Provide Energy • Starch: Food Reserve of Plants • Glycogen: Food Reserve of Animals • Cellulose: Important component of Plant Cell Wall

7. Nucleic Acids • Include DNA & RNA • Store information which controls cell activities • DNA: Mainly in Nucleus • RNA: In Cytoplasm & Nucleus

8. Minerals • Found in cells in form of Ions • For healthy functioning of organisms • Affect chemical reactions in cells • Plants: Obtain minerals from Soil • Animals: From Diet

9. METABOLISM

10. The concept of metabolism • Metabolism = all the chemical reactions taken place inside the living organisms • Metabolic reactions produce different life processes, e.g. • photosynthesis • respiration • movement • growth • reproduction

11. Types of metabolism • Catabolism: • break down complex organic molecules into simpler molecules • e.g. respiration:gives out energy

12. Types of metabolism • Anabolism: • Build up complex organic molecules from simple molecules • e.g. Photosynthesis:requires energy

13. Types of Enzymes • Extracellular Enzymes • leave the cell & exert actions • outside the cell Intracelluar Enzymes - exert action inside the cell

14. enzyme C A + B Control of metabolism • Metabolic reactions can be controlled and speeded up by enzymes • metabolic reactions would be too slow to occur if no enzymes are present!

15. Investigation 4.1 Detection of the presence of Catalase in Plant and Animal Tissues

16. liver potato meat apple boiled liver growing splint A B C D E 3 5cm of 3% hydrogen peroxide solution What is the purpose of setting up tube E ? Ans: To see whether the catalase in the tissue can still catalyse the decomposition of hydrogen peroxide after boiling.

17. liver potato meat apple boiled liver growing splint A B C D E 3 5cm of 3% hydrogen peroxide solution What gas is evolved when fresh tissues are added into the hydrogen peroxide solution ? Ans: Oxygen.

18. liver potato meat apple boiled liver growing splint A B C D E 3 5cm of 3% hydrogen peroxide solution Which tissue has the highest catalase activity ? Ans: Fresh liver tissue.

19. liver potato meat apple boiled liver growing splint A B C D E 3 5cm of 3% hydrogen peroxide solution What conclusion can you draw from the results of this experiment ? Ans: Catalase is produced by fresh tissues only. Boiling kills the cells and destroys the enzyme.

20. Protein Nature and properties of enzymes • Proteins in nature • Specific in action • one kind of enzyme will catalyse only one kind of chemical reaction • Biological Catalyst Biological-found within living organisms Catalyst-substance which can speed up a chemical reaction

21. Mechanism of enzyme action • Each enzyme has an active site

22. Mechanism of enzyme action • Active site: the place where substrate binds with the enzyme • Each active site can only allow specific substrate to fit in

23. Mechanism of enzyme action • The enzyme and substrate molecules combine to form a temporary structure calledenzyme-substrate complex

24. enzyme-substrate complex enzyme-product complex product substrate enzyme enzyme Action of enzyme (Anabolic reaction)

25. enzyme-product complex enzyme-substrate complex products substrate enzyme enzyme Action of enzyme (catabolic reaction)

26. Mechanism of enzyme action • The product molecules are then formed and they escape from the active site • The active site is free to attach to other substrate molecules again ( i.e. it can be reused )

27. This hypothesis to explain the specificity of enzyme action is called lock and key hypothesis

28. product Substrate product Enzyme Lock and key hypothesis

29. SHAPES DON’T MATCH Lock and key hypothesis

30. pH Nature and properties of enzymes • Catalyse reversible reaction in both directions • Enzymatic activity is affected by temperature and pH • high temperature and extreme pH can denature enzymes ∵ protein in nature

31. Effect of temperature on enzyme activity • Low temperature : low kinetic energy possessed by the substrate and enzyme molecules The enzyme becomes inactive Lower reaction rate (and enzyme activity)

32. Effect of temperature on enzyme activity

33. Effect of temperature on enzyme activity • Higher temperature : more kinetic energy possessed by the substrate and enzyme molecules Higher reaction rate (and enzyme activity)

34. Effect of temperature on enzyme activity • The temperature which allows the highest enzyme activity is called theoptimum temperature

35. Effect of temperature on enzyme activity • At temperature higher than the optimum temperature, the shape of the active site is changed The enzyme is said to be denatured substrate can no longer bind to the active site of the enzyme

36. Effect of temperature on enzyme activity

37. Effect of temperature on enzyme activity • Enzymes become inactive but not denatured at low temperatures They can regain catalytic function when the temperature increases

38. Effect of temperature on enzyme activity • Denaturation is a permanent process When an enzyme is denatured, its catalytic function is lost permanently, and cannot be restored ( never become active again ) even it is put in lower temperature

39. Effect of temperature on enzyme activity • Different enzymes may have different optimum temperature • The optimum temperature of many enzymes in human body is not 37oC, even though this is our body temperature! • Our body temperature can provide a better environment for all the enzymes in our bodies to work

40. Investigation 4.2 Effect of Temperature on the action of Amylase

41. A1 A2 B1 B2 C1 C2 D1 D2 ice bath at 2℃ water bath at 37 ℃ water at 100 ℃ water bath at room temperature amylase solution starch solution thermometer amylase and starch solution iodine solution spotting tile Why is it necessary to equilibrate the pair of test tubes under each condition for 5 minutes before mixing ? Ans: To ensure the pair of test tubes are in the same temperature.

42. A1 A2 B1 B2 C1 C2 D1 D2 ice bath at 2 ℃ water bath at 37 ℃ water at 100 ℃ water bath at room temperature amylase solution starch solution thermometer amylase and starch solution iodine solution spotting tile What is the factor affecting the action of amylase in converting starch into sugar ? Ans: Temperature.

43. A1 A2 B1 B2 C1 C2 D1 D2 ice bath at 2 ℃ water bath at 37 ℃ water at 100 ℃ water bath at room temperature amylase solution starch solution thermometer amylase and starch solution iodine solution spotting tile At which temperature does all the starch in the tube disappear first ? Ans: 37 ℃.

44. A1 A2 B1 B2 C1 C2 D1 D2 ice bath at 2 ℃ water bath at 37 ℃ water at 100 ℃ water bath at room temperature amylase solution starch solution thermometer amylase and starch solution iodine solution spotting tile How does the activity of amylase change with temperature ? Ans: At room temperature, amylase works but not as well as that at 37 ℃. It does not work at 2℃ and 100℃.

45. A1 A2 B1 B2 C1 C2 D1 D2 ice bath at 2 ℃ water bath at 37 ℃ water at 100 ℃ water bath at room temperature amylase solution starch solution thermometer amylase and starch solution iodine solution spotting tile At which temperature does amylase work best ? Ans: 37 ℃.

46. Effect of pH on enzyme activity • Optimum pH : the pH value at which the enzyme has the highest activity Too extreme pH can destroy the enzymes • pH of medium higher or lower than optimum pH can inactivate the enzyme

47. Enzyme 2 Enzyme 1 Enzyme 3 Different enzymes has different optimum pH Rate of reaction pH

48. Factors affecting Enzyme Activity & Rate of Enzymatic Reactions

49. Factors affecting enzyme activities : • Temperature • pH • Factors affecting rate of enzymatic reactions : • Temperature • pH • Enzyme concentration • Substrate concentration

50. Factors affecting enzyme action : Substrate concentration