Powerpoint enzymes

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Powerpoint enzymes

  1. 1. ENZYMES
  2. 2. 10 Enzymes-Enzymes are proteins that function as biological catalysts-Catalyst: a substance that speeds up a chemical reactionand is not changed by the reaction.They are present in the cytoplasm of all cellsThere are hundreds of different enzymes but each enzymespeeds up only one kind of reaction. They are specific.For example, glucose and fructose might join up slowly toform sucrose glucose- -fructose With the right enzyme present, the reaction happens faster glucose- -fructose
  3. 3. 12The substrate molecules fit the shape of the enzyme enzyme substrate A substrate B
  4. 4. 13
  5. 5. 14substrates combine temporarily with enzyme enzyme joins substrates together
  6. 6. 15enzyme unchanged new compound releasedand ready for by enzymenext reaction
  7. 7. 16Different types of enzyme reaction The last 4 slides show how an enzyme is involved in combining substrates to create a larger molecule For example, the enzyme could be building up a sucrose molecule from glucose and fructose (anabolic reaction) The next sequence shows how an enzyme can help to break a large molecule into smaller molecules (catabolic reaction) For example an enzyme can split a sucrose molecule into the smaller glucose and fructose molecules
  8. 8. 17 A ‘breaking-down’ reaction the shape of the substrate molecule fits the enzyme shapethis is calledthe active siteof the enzyme
  9. 9. 18Intermediate stage (1) substrate combines temporarily with enzyme enzyme will break molecule here
  10. 10. 19Intermediate stage (2) substrate splits and separates from enzyme
  11. 11. 20Final break-down products enzyme ready for next reaction end-products
  12. 12. 21 Properties of enzymes -Enzymes can act on only one type of substrate (specific) -They always produce the same end products -Although they take part in the reaction, they are not used up -Because enzymes are proteins, they are denatured by heat or some chemicalsDenaturing involves a change of shape in the enzymemolecule so that it cannot combine with the substrateIndividual enzymes work best at a particular temperatureand pH (acidity or alkalinity)
  13. 13. 22Enzymes can act on only one type of substrate this substrate cannot combine with this enzyme this substrate cannot combine with this enzyme
  14. 14. Because enzymes are proteins, they are denatured by 23heat or some chemicals enzyme enzyme + denatured substrate by heat denatured enzyme cannot combine with substrate
  15. 15. ENZYME ACTION 24 1 E 1. A glucose molecule combines with glucose the active site on an enzyme molecules
  16. 16. ENZYME ACTION 24 1 E 1. A glucose molecule combines with glucose the active site on an enzyme molecules
  17. 17. 25 E2 A region of the active site is still available
  18. 18. 263 One end of a growing starchmolecule combines with theglucose molecule at the active part of starchsite molecule E
  19. 19. 274 The growing starch molecule breaksfree from the enzyme which is now freeto repeat the reaction E
  20. 20. 28Enzyme action 11 2 E E part of starch moleculeglucose E 3molecules E E E 4
  21. 21. Enzyme activityHow fast an enzyme is working Rate of Reaction
  22. 22. Enzyme activity How fast an enzyme is working Rate of ReactionRate of Reaction = Amount of substrate changed (or amount product formed) in a given period of time.
  23. 23. Enzyme activityRate of Reaction Variable you are looking at
  24. 24. Enzyme activityFour Variables
  25. 25. Enzyme activity Temperature pHFour Variables Enzyme Concentration Substrate Concentration
  26. 26. Rate of Reaction Temperature
  27. 27. TemperatureRate of Reaction 0 10 20 30 40 50 60
  28. 28. 5- 40oC Temperature Increase in Activity 40oC - denatures Rate of Reaction 0 10 20 30 40 50 60<5oC - inactive
  29. 29. Effect of heat on enzyme activty If you heat the protein above its optimal temperature bonds breakmeaning the protein loses it secondary and tertiary structure
  30. 30. Effect of heat on enzyme activty Denaturing the protein
  31. 31. ph• The ph scale measures how acidic or alkaline a substance is.• The chemical properties of many solutions enable them to be divided into 3 categories: 1) Neutral: solutions with a ph of 7. 2) Alkaline: solutions with a ph greater than 7 3) Acidic: solutions with a ph less than 7.
  32. 32. Ph scale
  33. 33. Rate of Reaction pH
  34. 34. Rate of Reaction12345 pH6789
  35. 35. pH Narrow pH optimaRate of Reaction 1 2 3 4 5 6 7 8 9
  36. 36. pH Narrow pH optimaRate of Reaction WHY? 1 2 3 4 5 6 7 8 9
  37. 37. pH Narrow pH optima Disrupt Ionic bonds - StructureRate of Reaction Effect charged residues at active site 1 2 3 4 5 6 7 8 9
  38. 38. Enzyme Concentration Rate of Reaction
  39. 39. Enzyme Concentration Rate of Reaction Enzyme Concentration
  40. 40. Substrate Concentration Rate of Reaction
  41. 41. Substrate Concentration Rate of Reaction Substrate Concentration
  42. 42. Substrate Concentration Active sites full- maximum turnover Rate of Reaction Substrate Concentration
  43. 43. 37 Question 1Enzymes are(a) proteins(b) lipids(c) carbohydrates(d) a combination of these
  44. 44. 38 Question 2An enzyme can(a) change a reaction(b) prevent a reaction(c) slow down a reaction(d) speed up a reaction
  45. 45. 39 Question 3 A substrate is a substance which(a) an enzyme acts on(b) is produced by an enzyme reaction(c) is a particular kind of enzyme(d) is any chemical substance in a cell
  46. 46. 40 Question 4 An enzyme can(a) combine with different substrates(b) form different kinds of end-product(c) function at temperatures above 90oC(d) speed up a reaction in the cytoplasm
  47. 47. 41 Question 5The part of an enzyme which combines with the substrateis called(a) the reaction centre(b) the active site(c) the action centre(d) the reaction site
  48. 48. 42 Question 6After being exposed to a high temperature an enzymecannot function because (a) it has been broken down (b) its shape has been changed (c) its composition has been changed (d) it cannot separate from its substrate

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