MENU OF THE DAY

1. MENU OF THE DAY

2. SIZE TEMPER SPEED HEIGHT

3. Enzymes’

4. Enzyme Characteristic 1 Enzymes _________ __________ chemical reactions. speed up

5. Enzyme Characteristic 2 Tube A Tube B Tube C

6. Enzymes are required in minute amounts. Tube A Tube B Tube C Minute amountsof enzymes is needed to speed up the rate of reaction, without being chemically changed at the end of the reaction.

7. Maltase Enzymes are required in minute amounts. At the end of a chemical reaction, enzymes remain chemically unchanged and capable of catalysing more reactions. Glu Glu Maltose

8. Maltase Enzymes are required in minute amounts. At the end of a chemical reaction, enzymes remain chemically unchanged and capable of catalysing more reactions. Glu Glu Maltose

9. Maltase Enzymes are required in minute amounts. At the end of a chemical reaction, enzymes remain chemically unchanged and capable of catalysing more reactions. Glu Glu Maltose

10. Maltase Enzymes are required in minute amounts. At the end of a chemical reaction, enzymes remain chemically unchanged and capable of catalysing more reactions. Glu Glu Maltose

11. Maltase Enzymes are required in minute amounts. Since enzymes remain chemicallyunchanged in the reactions they catalyse, the same enzyme can be used over and over again. Glu Glu Hence, a minute amount of enzymes is enough to catalyse a chemical reaction. Maltose

12. Recall How do we name enzymes? Based on the substrate they act on!

13. Enzyme Characteristic 3 Amylase ACT ON Starch Protease ACT ON Proteins Substrates Lipase Lipids/ Fats ACT ON Enzymes are substrate specific.

14. Enzyme Characteristic 3 An Enzyme

15. Enzyme Characteristic 3 A depression on the surface of an enzyme molecule into which the substrate molecule(s) can fit The specificity of an enzyme is due to its surface configuration or active site. Active site

16. Lock & Key Hypothesis Demonstration

17. Lock & Key Hypothesis According to the “lock and key” hypothesis, the enzyme action depends on the active site.

18. Lock & Key Hypothesis B A Unsuitable substrate molecules will NOT FIT into the active site.Hence, the enzyme will not catalyse the reaction.

19. CD Lock & Key Hypothesis D C ONLY suitable substrate molecules will fit into the active site.The enzyme will then be able to catalyse the reaction.

20. Lock & Key Hypothesis Only certain substrate can fit the active site of an enzyme.

21. Lock & Key Hypothesis lock key

22. Lock & Key Hypothesis key lock The formation of enzyme-substrate complexwill lower the activation energy and brings about the necessary reactions converting the substrate molecules into product molecules.

23. What is Activation Energy? The energy that must be overcome in order for a chemicalreaction to occur. Energy Activation energy for a reaction without a catalyst (enzyme) reactants products Time

24. What is Activation Energy? The energy that must be overcome in order for a chemical reaction to occur. Energy Activation energy for a reaction with a catalyst (enzyme) reactants products Time

25. Lock & Key Hypothesis • Each enzyme is a molecule with a specific shape. • On part of its surface is the active site (the lock)—a section where its substrate molecule (the key)fits exactly.

26. Lock & Key Hypothesis • When the substrate molecule is in position in the active site, the enzyme alters the substrate, splitting it into its product molecules.

27. Lock & Key Hypothesis • The product molecules drift away from the enzyme molecule leaving its active site freeto operate again.

28. Lock & Key Hypothesis

29. Hmm… enzymes seemed to be so powerful… Is there anything that can affect it?

31. Temperature

32. pH

33. Temperature pH

34. Temperature

35. Temperature What happens to the movement of the enzymes and substrates as temperature increases? Ans: The movement of the enzymes and substrates increases, resulting in higher collision rates. Why do you think the rate of enzymatic reaction increases as temperature increases? Ans: The increase in collision rates results in an increase in the formation of enzyme-substrate complex, thereby resulting in an increase in the rate of enzymatic reaction.

36. Temperature Which temperature do you think is the optimum temperature? What happens to the enzyme when the temperature exceeds that particular temperature? What do you think is the meaning of optimum temperature? Ans: 40 °C. The enzymes are denatured. The optimum temperature is the temperature at which the enzyme is most active, catalysing the largest number of reactions per second. What does ‘denatured’ mean? Ans: Its structure had been irreversibly changed.

37. Rate of reaction (enzyme activity) Enzyme is most active at its optimum temperature As the temperature rises, rate of reaction increases due to increase in enzyme activity. The enzyme is twice as active for every 10°C rise in temperature until the optimum temperature is reached 3 2 Beyond optimum temperature, enzyme activity decreases 4 Zero enzyme activity lost its ability to catalyse the reaction 1 Enzyme is less active at very low temperatures 5 0 Temperature

38. pH

39. pH What happens to the enzymes as the pH increases above 7? Ans: The enzymes began to denature. What happens to the enzymes as the pH decreases above 7? Ans: The enzymes began to denature. Which pH do you think is the optimum pH? Ans: pH 7. At what pH levels are the enzymes completely denatured? Ans: pH 4 and pH 9.

40. pH • Optimum pH usually at pH 7 but different enzymes have varying optimum pH • Some work best in slightly acidic solutions:- rennin and pepsin (stomach) • Some work best in slightly alkaline solutions – intestinal enzymes

41. Denaturation Denatured protein! Active site is lost! Active site It is the change in the three-dimensional structure of an enzyme or any other soluble protein, caused by heat or chemicals such as acids or alkalis.

42. What we learn today. • Characteristics of Enzymes (Think: What are they?) • What is Activation Energy? • “Lock and Key” Hypothesis (Describe) • Temperature and Enzymes (How does temperature influence the enzymes?) • pH and Enzymes (How does pH influence the enzymes?)