Powerpoint, anim,enzymes, click bio


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Powerpoint, anim,enzymes, click bio

  1. 1. Biological catalystsIGCSE Biology (Cambridge)
  2. 2.  A catalyst is a substance that speeds up the rate ofa chemical reaction but is not itself changed by thereaction.
  3. 3. hydrogen peroxideHydrogen peroxide breaks down to water and oxygenThe escaping oxygen causes the foaming2H2O2 2H2O O2+water + oxygenmanganese oxide
  4. 4.  They occur inside cells or are secreted by the cells. Catalase is the enzyme that catalyses the breakdown of hydrogen peroxide.Enzymes act as biological catalystsCatalase
  5. 5.  Proteins are long molecules that are folded into a specific shape.catalase amylase trypsinpepsinEnzymes are proteins
  6. 6. Active site:Enzyme
  7. 7. Active site:The site on theenzyme where thereaction occursEnzymeSubstrate molecules
  8. 8. Active site:The site on theenzyme where thereaction occursEnzymeProduct molecules
  9. 9.  The lock and key hypothesis states that the active site specificallymatches the shape of the substrate moleculeenzymeEach enzyme is specific to one substrate moleculeor type of moleculeactive site
  10. 10.  At low temperatures enzyme controlled reactions go slowlybecause the molecules have low kinetic energy.The rate of an enzyme controlled reaction isaffected by temperature
  11. 11. But this only occurs up to theoptimum temperature(usually about 40oC)The temperature at whichthe rate of reaction isfastest is known as theoptimum temperatureWhen temperature increases the reaction alsoincreases as the molecules have more kinetic energy
  12. 12. After the optimum temperature the heat causesthe enzyme to denature The enzyme changes shape and the active site no longer matchesthe shape of the substrate molecule
  13. 13. protein polypeptidestrypsinwhite clearControlled variables:•Volume and concentration of substrate (milk)•Volume and concentration of enzyme (trypsin)•pH (controlled by buffers)•Temperature
  14. 14. RateOfReactionTemperature/oC0 10 20 30 40 50 60 70Optimum temperatureEnzymeis denaturingRate of reaction of an enzyme reaction changesat different temperaturesMolecules gainkinetic energy
  15. 15.  Enzymes prefer to work at an optimum pH. Outside of its pH rangethe enzyme is denatured.RateOfReactionpH1 2 3 4 5 6 7 8 9 10 11 12pepsin amylaseThe activity and shape of enzymes is alsoaffected by pHOptimum pH
  16. 16.  Proteases break down the coloured, insoluble proteins thatcause stains to smaller, colourless soluble polypeptides. Can wash at lower temperatures
  17. 17.  Pectinase break down substances inapple cell walls and enable greaterjuice extraction. Lactase breaks down lactose in milkinto glucose and galactose.This makes milk drinkable for lactoseintolerant people.
  18. 18. starchembryo plantamylasesecretedmaltoseabsorbed
  19. 19.  Keywords:enzymeactive sitesubstrate productdenaturetemperaturepHoptimumcatalase amylasetrypsin pepsinpectinaselactaseproteasecatalyst catalyse protein
  20. 20. www.clickbiology.com