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AS-U1-2.6 Enzyme action


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AS-U1-2.6 Enzyme action

  1. 1. Enzyme Action Objective: To understand the role of enzymes in the body and how they function. Outcomes: Recall the function of enzymes. Describe the structure of enzymes. Compare the two different models that explain how enzymes work. Sunday, 28 September 2014 Keywords Active site Substrate Enzyme-substrate complex Lock and key model Induced fit model
  2. 2. Enzymes Globular proteins that catalyse chemical reactions in living organisms (biological catalysts): Properties Specific (tertiary protein structure) Increase rate of the reaction Unchanged at the end of the reaction Need them Reactions too slow to maintain life
  3. 3. Enzymes are specific A substrate is a reactant which binds to an enzyme. When a substrate or substrates binds to an enzyme, the enzyme catalyzes the conversion of the substrate to the product. e.g. Sucrase is an enzyme that binds to sucrose and breaks the disaccharide into fructose and glucose.
  4. 4. The active site of an enzymes is typically a pocket or groove on the surface of the protein into which the substrate fits. The specificity of an enzyme is due to the fit between the active site and that of the substrate.
  5. 5. Models of enzyme action The lock and key model The induced fit model Use page 31 and 32 to create a table/diagram/notes summarising the differences between these two models of enzyme action.
  6. 6. The lock and key model Substrate molecules Enzyme is rigid. Active site Enzyme Reaction happens (bonds either made or broken) Product Enzymes have a specific 3D structure Enzyme-substrate complex
  7. 7. But… Other molecules could bind to enzymes at different sites. This altered the activity of the enzyme. The enzyme was flexible.
  8. 8. Models of enzyme action The induced fit model • The active site fits to the substrate, and the enzyme changes shape slightly. • This interaction is called induced fit.
  9. 9. Enzyme Action Scientists often try to explain their observations by producing a representation of how something works. This is known as a scientific model. The lock and key model The induced fit model