enzymes notes

• Metabolism


  Sum of chemical reactions that take place in an organism
• Catabolism


  • Breaking down + energy release
  • Complex molecules broken down into simpler molecules
  • Respiration
• Anabolism


  • Building up
  • Energy required
  • Simpler molecules synthesized into complex molecules
  • Photosynthesis
• Enzyme


  Biological catalyst
• Question examples


  • Reactants
  • Products
  • Progress of reaction
  • Activation energy without enzyme
  • Reactivation energy with enzyme
• The energy level of products is less than that of reactants, indicating that energy is released during the reaction
• Greater amount of activation energy required for reaction

  Rate of reaction will be slower
• Enzyme present


  Activation energy needed for reaction is lower
• Importance of enzymes in our body

  • Can lower the activation energy so that chemical reactions can take place at body temp at faster rate
  • Substrate molecule bind to enzyme, enzyme substrate molecule greatly lowers activation energy
  • Substrate molecule converted into product, product leaves the site, enzyme back to original form, can be reused
• Properties of enzymes


  • Biological catalysts
  • Speed up metabolic reaction by lowering activation energy
  • Enzymes are proteins, denatured at high temp
  • Structure/activity affected by extreme temp/pH
  • Enzyme is specific in action, only substrate that binds to site have reaction, each enzyme catalyse one type of reaction only, unique active site
  • Reusable, site of reaction does not change
  • Needed in small amounts, can be reused
• Factors affecting enzyme activity

  • Temperature: Optimum temp, low temp inactive, high temp activity decreases rapidly
  • pH: Optimum pH, low/high pH activity decreases, denaturation
• Inhibitors


  Substances that decrease the activity of enzymes
• Inhibitors


  • Cyanide: Prevent respiration, prevent enzyme from working properly
  • Heavy metals: Mercury ions, lead ions, copper ions, affect metabolism