Chapter 4  Enzymes
Lesson Objectives <ul><li>Definition of  catalysts </li></ul><ul><li>Definition of  enzymes </li></ul><ul><li>Roles of enz...
BBQ
<ul><li>Qn :  Why do chefs add pineapple juice/ unripe papaya juice to meat? </li></ul>Qn :  What is the purpose of adding...
Marinades <ul><li>Tenderizing marinades makes leaner cuts of meat   more tender and juicy </li></ul><ul><li>Contents in th...
What are enzymes? <ul><li>Protein in nature (most enzymes!) </li></ul><ul><li>biological  catalysts </li></ul><ul><li>(A  ...
How do enzymes alter the rate of chemical reactions? <ul><li>The energy needed to start a chemical reaction is called  act...
time
Terms to know: substrate : substances on which enzymes act upon Note the surface configuration/shape of the substrate & en...
Lock & Key Hypothesis
 
+
synthetase hydrolase
Based on lock and key hypothesis… <ul><li>Enzymes </li></ul><ul><li>alter the rates of reaction </li></ul><ul><li>are spec...
Roles of enzymes <ul><li>digestion </li></ul><ul><li>synthesis of complex substances </li></ul><ul><li>hydrolysis of compl...
1) Digestion <ul><li>3 main   classes of food  we eat </li></ul><ul><li>Carbohydrates </li></ul><ul><li>Proteins </li></ul...
Digestion <ul><li>Involves  breakdown  of  </li></ul><ul><li>Carbohydrates    simple sugars </li></ul><ul><li>Proteins  ...
Carbohydrate Carbohydrates Monosaccharides Disaccharides Polysaccharides (simple sugars) (complex sugars) starch cellulose...
Disaccharides & Monosaccharides maltase lactase sucrase glucose  + fructose Sucrose glucose  + galactose Lactose glucose  ...
Hydrolysis <ul><li>Break down of complex molecules into simpler molecules  </li></ul><ul><li>Water molecules are needed fo...
Enzymes Active site : the substrate binding site of an enzyme  The shape of the substrate has to be  complementary  to the...
2) Synthesis of complex substances <ul><li>Composed entirely of glucose units </li></ul><ul><li>Yet have different propert...
3) Breakdown of complex substances Chemical reactions produce H 2 O 2 H 2 O 2  is toxic to tissues Cells produce catalase ...
Potato + hydrogen peroxide  <ul><li>Where is the source of catalase? </li></ul><ul><li>A slice of potato or a drop of bloo...
Classification of enzymes
Many classes <ul><li>Hydrolases e.g. digestive enzymes </li></ul><ul><ul><li>-  carbohydrases  e.g. amylase (digest starch...
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Chapter 5 Enzymes Lesson 1 - Introduction to Enzymes

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Chapter 5 Enzymes Lesson 1 - Introduction to Enzymes

  1. 1. Chapter 4 Enzymes
  2. 2. Lesson Objectives <ul><li>Definition of catalysts </li></ul><ul><li>Definition of enzymes </li></ul><ul><li>Roles of enzymes </li></ul><ul><li>Enzymes found at home </li></ul><ul><li>Characteristics of enzymes </li></ul>
  3. 3. BBQ
  4. 4. <ul><li>Qn : Why do chefs add pineapple juice/ unripe papaya juice to meat? </li></ul>Qn : What is the purpose of adding the juices? Qn : Can any juice be used for the same function?
  5. 5. Marinades <ul><li>Tenderizing marinades makes leaner cuts of meat more tender and juicy </li></ul><ul><li>Contents in the marinade that tenderize the meat can come from </li></ul><ul><li>1) acidic foods like lemon juice, yogurt, wine, or vinegar </li></ul><ul><li>OR </li></ul><ul><li>2) natural enzymes found in fresh papaya, ginger, pineapple, and figs. </li></ul>
  6. 6. What are enzymes? <ul><li>Protein in nature (most enzymes!) </li></ul><ul><li>biological catalysts </li></ul><ul><li>(A catalyst is a substance that alters or speeds up a chemical reaction , without itself being chemically changed at the end of the reaction) </li></ul><ul><li> therefore required in small quantities </li></ul>
  7. 7. How do enzymes alter the rate of chemical reactions? <ul><li>The energy needed to start a chemical reaction is called activation energy </li></ul><ul><li>Enzymes lower the activation energy required to start a chemical reaction </li></ul>
  8. 8. time
  9. 9. Terms to know: substrate : substances on which enzymes act upon Note the surface configuration/shape of the substrate & enzymes Enzyme-substrate complex
  10. 10. Lock & Key Hypothesis
  11. 12. +
  12. 13. synthetase hydrolase
  13. 14. Based on lock and key hypothesis… <ul><li>Enzymes </li></ul><ul><li>alter the rates of reaction </li></ul><ul><li>are specific </li></ul><ul><li>are required in minute amounts </li></ul>
  14. 15. Roles of enzymes <ul><li>digestion </li></ul><ul><li>synthesis of complex substances </li></ul><ul><li>hydrolysis of complex substances </li></ul><ul><li>e.g. hydrolysis by catalase </li></ul>
  15. 16. 1) Digestion <ul><li>3 main classes of food we eat </li></ul><ul><li>Carbohydrates </li></ul><ul><li>Proteins </li></ul><ul><li>Fats </li></ul><ul><li>Molecules are: </li></ul><ul><li>Large </li></ul><ul><li>Insoluble </li></ul><ul><li>Non-diffusible molecules </li></ul>
  16. 17. Digestion <ul><li>Involves breakdown of </li></ul><ul><li>Carbohydrates  simple sugars </li></ul><ul><li>Proteins  amino acids </li></ul><ul><li>Fats  fatty acids + glycerol </li></ul><ul><li>Brought about by action of digestive enzymes </li></ul><ul><li>Converted into: </li></ul><ul><li>small </li></ul><ul><li>soluble </li></ul><ul><li>diffusible molecules </li></ul>
  17. 18. Carbohydrate Carbohydrates Monosaccharides Disaccharides Polysaccharides (simple sugars) (complex sugars) starch cellulose glycogen e.g. maltose, lactose, sucrose e.g. glucose, galactose, fructose
  18. 19. Disaccharides & Monosaccharides maltase lactase sucrase glucose + fructose Sucrose glucose + galactose Lactose glucose + glucose Maltose Monosaccharide Disaccharide
  19. 20. Hydrolysis <ul><li>Break down of complex molecules into simpler molecules </li></ul><ul><li>Water molecules are needed for the process </li></ul>
  20. 21. Enzymes Active site : the substrate binding site of an enzyme The shape of the substrate has to be complementary to the active site for the chemical reaction to take place
  21. 22. 2) Synthesis of complex substances <ul><li>Composed entirely of glucose units </li></ul><ul><li>Yet have different properties </li></ul><ul><li>Due to differential arrangement </li></ul>(plants) (plants) (humans)
  22. 23. 3) Breakdown of complex substances Chemical reactions produce H 2 O 2 H 2 O 2 is toxic to tissues Cells produce catalase Catalase breaks down hydrogen peroxide  water and oxygen
  23. 24. Potato + hydrogen peroxide <ul><li>Where is the source of catalase? </li></ul><ul><li>A slice of potato or a drop of blood will cause hydrogen peroxide to fizz (form bubbles) </li></ul>source of catalase Hydrogen peroxide Bubbling in H 2 O 2
  24. 25. Classification of enzymes
  25. 26. Many classes <ul><li>Hydrolases e.g. digestive enzymes </li></ul><ul><ul><li>- carbohydrases e.g. amylase (digest starch), cellulase (digest cellulose) </li></ul></ul><ul><ul><li>- proteases (digest proteins) </li></ul></ul><ul><ul><li>- lipases (digest fats a.k.a lipids) </li></ul></ul><ul><li>Oxidation-reduction enzymes </li></ul>

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