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OptimumSubstrate Protein Unchanged Temperature Specific Product pH Active site Catalyst.

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Presentation on theme: "OptimumSubstrate Protein Unchanged Temperature Specific Product pH Active site Catalyst."— Presentation transcript:

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2 OptimumSubstrate Protein Unchanged Temperature Specific Product pH Active site Catalyst

3 Chemical reactions in a living cell Metabolic reactions Normally too slow to sustain life. SUBSTRATE(S) reaction PRODUCT(S) Catalysts speed up reactions

4 Catabolic reactions break down molecules eg digestion Metabolism Anabolic reactions build up molecules eg photosynthesis

5 Enzymes are proteins which act as biological catalysts – they speed up biological reactions which otherwise would be too slow to sustain life Enzymes Enzymes are usually Specific for a substrate or group of substrates (the chemicals they act on) Enzymes are unchanged by reaction Summary

6 Enzyme- substrate complex ENZYMESUBSTRATEPRODUCT Enzyme brings reactive parts of substrates together for reaction to occur

7 Enzyme- substrate complex ENZYMESUBSTRATEPRODUCT Enzyme brings reactive parts of substrate together for reaction to occur Summary

8 Enzyme will only bind substrates that fit exactly into the active site Lock and Key model SUBSTRATE enzyme Enzyme-SUBSTRATE complex products e.com/watch?v=C ZD5xsOKres&feat ure=related

9 Induced fit model Substrate causes shape change in active site SUBSTRATE Enzyme-SUBSTRATE complex products /Video/Enzyme- Action-The-Induced- Fit-Model http://www.5min.com /Video/Enzyme- Action-The-Induced- Fit-Model (12 min)

10 Theories of enzyme action COMPARE: In both models an enzyme-substrate complex is formed the activation energy is lowered enzyme remains unchanged afterwards substrate products CONTRAST: In lock and key model substrate must fit active site exactly in order to bind, whereas with the induced fit model the substrate can cause active site to change slightly to allow a fit. Summary

11 Denaturing proteins Certain conditions permanently break bonds that hold the enzymes 3D shape. Active site shape destroyed enzyme high temperature cannot function Summary

12 Activation Energy Reactions require energy to get them going To get the ball to B, you need to give it enough energy to get over the top – even though B is lower than A A B

13 Activation Energy A B Enzymes lower the activation energy required to start a reaction Summary LrRM&feature=relatedhttp://www.youtube.com/watch?v=VbIaK6P LrRM&feature=related (1 min)

14 MENU Key Words Exercises Quick Quiz MCQ VideosRecap Extra slides

15 Key words Metabolism Substrate Product Reaction rate Enzyme Globular protein Biological catalyst 3D structure Denaturation Active site Specificity Enzyme-substrate complex Lock and Key model Induced fit model Exergonic Endergonic Activation energy Back to menu

16 Quick quiz 1.Chemical reactions in living cells are _____ reactions 2.____ reactions build up molecules 3.____ reactions break down molecules 4.____ speed up reactions 5.____ are biological catalysts 6.Enzymes are made of ____ 7.Enzymes are ____-shaped 8.Enzyme function depends on its ____ 9.The ____ site of the enzyme binds with the substrate 10.____ model: substrate must fit exactly into the enzyme 11.____ model: enzyme shape can change to fit 12.Enzymes lower the ____ required to initiate a reaction Back to menu Answers

17 Quick quiz 1.Chemical reactions in living cells are metabolic reactions 2.Anabolic reactions build up molecules 3.Catabolic reactions break down molecules 4.Catalysts speed up reactions 5.Enzymes are biological catalysts 6.Enzymes are made of protein 7.Enzymes are globular-shaped 8.Enzyme function depends on its shape 9.The active site of the enzyme binds with the substrate 10.Lock and key model: substrate must fit exactly into the enzyme 11.Induced fit model: enzyme shape can change to fit 12.Enzymes lower the activation energy required to initiate a reaction Back to menu

18 Exercise Workbook pp 50-1, qq15-17 Pathfinder pp44-5 (or 50-51) qq 3-6 EXTRA READING Pathfinder p48 (or p42) Proteins and Enzymes Excellence in Biology p Booklet p3 Back to menu

19 Videos Back to menu &feature=relatedhttp://www.youtube.com/watch?v=E90D4BmaVJM &feature=related (10 min, includes biotechnology) tch?v=MUtfF2qnzGo&fe ature=related tch?v=MUtfF2qnzGo&fe ature=related (metabolism1, 6 min) tch?v=AEsQxzeAry8&fe ature=relatedhttp://www.youtube.com/wa tch?v=AEsQxzeAry8&fe ature=related (digestion by enzymes, 3min)

20 Question 1 High temperatures damage proteins by (a) decomposing them (b) changing their chemical composition (c) changing their shape (d) making them soluble 34 Back to menu

21 Question 2 A protein is made up of a series of (a) glucose units (b) fatty acids (c) amino acids (d) carbohydrates 35 Back to menu

22 Question 3 Enzymes are (a) proteins (b) lipids (c) carbohydrates (d) a combination of these 37 Back to menu

23 Question 4 An enzyme can (a) change a reaction (b) prevent a reaction (c) slow down a reaction (d) speed up a reaction 38 Back to menu

24 Question 5 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 39 Back to menu

25 Question 6 An enzyme can (a) combine with different substrates (b) form different kinds of end-product (c) function at temperatures above 90 o C (d) lower the activation energy needed for a reaction 40 Back to menu

26 Question 7 The part of an enzyme which combines with the substrate is called: (a) the reaction centre (b) the active site (c) the action centre (d) the reaction site 41 Back to menu

27 Question 8 After being exposed to a high temperature an enzyme cannot 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 42 Back to menu

28 ANSWER Correct 43 click arrow to return Back to menu

29 ANSWER Incorrect X 44 click arrow to return Back to menu Oooops!

30 RECAP Back to Menu Your choice Copy diagrams from Workbook p50 or Pathfinder p42 Highlight key ideas in your workbook Add key words and definitions to your glossary Summarise the notes on enzymes from workbook & pathfinder Past Papers Q2

31 3-dimensional enzyme structure Globular proteins Globular proteins – long polypeptides held in shape by various bonds between side groups (eg hydrogen and ionic bonds) to form globules (ball-shaped) Polypeptide = chain of amino acids Back to Menu

32 SUBSTRATE enzyme Enzyme-SUBSTRATE complex enzyme products Lock and Key Model Back to Menu

33 SUBSTRATE enzyme Enzyme-SUBSTRATE complex enzyme products Induced Fit Model Back to Menu

34 Exergonic reactions Substrates have more energy than the products eg respiration breaks down sugar to r rr release energy ENERGY REACTION Back to Menu

35 Endergonic reactions Substrates have less energy than the products ENERGY REACTION eg photosynthesis uses solar energy to make sugar Back to Menu

36 Activation energy Nett energy released by reaction Free energy Time Activation energy Nett energy used by reaction Free energy Time Exergonic Energy released by reaction Endergonic Energy used by reaction Back to Menu

37 The end………………………. Back to menu


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