3ero 4 enzymes mine

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lesson on enzymes

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3ero 4 enzymes mine

  1. 1. Biological catalysts
  2. 2.  A protein which acts as a catalyst, which speeds up the rate of reaction. *All proteins are composed of sub-units called amino acids. *Proteins contain the elements carbon, hydrogen, oxygen, nitrogen and sulphur.
  3. 3. Enzymes are special proteins *There are hundreds of different enzymes but *With the right enzyme present, the reaction happens 10 faster each enzyme speeds up only one kind of reaction *Like all proteins, each enzyme molecule has a particular shape *Any substance an enzyme acts on is called a substrate
  4. 4. enzyme substrate A substrate B The substrate molecules fit the shape of the enzyme 12
  5. 5. 13
  6. 6. substrates combine temporarily with enzyme enzyme joins substrates together 14
  7. 7. new compound released by enzyme enzyme unchanged and ready for next reaction 15
  8. 8. The last 4 slides show how an enzyme is involved in combining substrates to create a larger molecule ANABOLISM (a sucrose molecule from glucose + fructose) The next sequence shows how an enzyme can help to break a large molecule into smaller molecules CATABOLISM (a sucrose molecule into glucose and fructose molecules) 16
  9. 9. the shape of the substrate molecule fits the enzyme shapethis is called the active site of the enzyme 17
  10. 10. substrate combines temporarily with enzyme enzyme will break molecule here 18
  11. 11. substrate splits and separates from enzyme 19
  12. 12. end-products enzyme ready for next reaction 20
  13. 13. 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 chemicals Denaturing involves a change of shape in the enzyme molecule so that it cannot combine with the substrate Individual enzymes work best at a particular temperature and pH (acidity or alkalinity) 21
  14. 14. this substrate cannot combine with this enzyme this substrate cannot combine with this enzyme 22
  15. 15. enzyme denatured by heat denatured enzyme cannot combine with substrate enzyme + substrate 23
  16. 16.  A catalyst is a substance that speeds up the rate of a chemical reaction but is not itself changed by the reaction.
  17. 17.  Proteins are long molecules that are folded into a specific shape. catalase amylase trypsinpepsin Enzymes are proteins
  18. 18. Active site: Enzyme
  19. 19. Active site: The site on the enzyme where the reaction occurs Enzyme Substrate molecules
  20. 20. Active site: The site on the enzyme where the reaction occurs Enzyme Product molecules
  21. 21.  The lock and key hypothesis states that the active site specifically matches the shape of the substrate molecule enzyme Each enzyme is specific to one substrate molecule or type of molecule active site
  22. 22.  Enzymes will usually react with only one substance.This can be explained by the 'lock and key' theory. If this theory is correct, which of the following substances, represented by P, Q, R and S would be acted on by enzyme A?
  23. 23.  Enzymes will usually react with only one substance.This can be explained by the 'lock and key' theory. If this theory is correct, which of the following substances, represented by P, Q, R and S would be acted on by enzyme A?
  24. 24.  At low temperatures enzyme controlled reactions go slowly because the molecules have low kinetic energy. The rate of an enzyme controlled reaction is affected by temperature
  25. 25. But this only occurs up to the optimum temperature (usually about 40oC) The temperature at which the rate of reaction is fastest is known as the optimum temperature When temperature increases the reaction also increases as the molecules have more kinetic energy
  26. 26. After the optimum temperature the heat causes the enzyme to denature  This means that cross linkages break and the enzyme changes properties and shape and the active site no longer matches the shape of the substrate molecule + than 40° C => cross linkages break down/loses shape and properties DENATURALIZATION
  27. 27. (HOW HOT SHOULD HE BE?)
  28. 28. Rate Of Reaction Temperature/oC 0 10 20 30 40 50 60 70 Optimum temperature Enzyme is denaturing Rate of reaction of an enzyme reaction changes at different temperatures Molecules gain kinetic energy
  29. 29.  PH is a measure of ACIDITY (-7) or ALKALINITY (+7)and is a mathematical method for expressing the concentration of H+ ions in solution.  Most enzymes work best at a ph of 7/They are affected by extremes of ph -- Exceptions: pepsin ph2 amylase ph 7 or +7
  30. 30.  Enzymes prefer to work at an optimum pH. Outside of its pH range the enzyme is denatured. Rate Of Reaction pH 1 2 3 4 5 6 7 8 9 10 11 12 pepsin amylase The activity and shape of enzymes is also affected by pH Optimum pH
  31. 31.  Proteases break down the coloured, insoluble proteins that cause stains to smaller, colourless soluble polypeptides.  Can wash at lower temperatures
  32. 32.  Pectinase break down substances in apple cell walls and enable greater juice extraction.  Lactase breaks down lactose in milk into glucose and galactose. This makes milk drinkable for lactose intolerant people.
  33. 33. a) membrane system b) mitochondria c) special vacuoles d) cytoplasm
  34. 34.  Keywords: enzyme active sitesubstrate product denaturetemperature pH optimum catalase amylase trypsin pepsinpectinase lactase protease catalyst catalyse protein

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