3.2

• Conditions for a chemical reaction to occur

  1. Reacting particles need to collide with enough energy to break the bonds - activation energy

  2. Particles must collide so the correct atoms come into contact
• At any given temperature

  There is a certain proportion of particles that have enough energy to satisfy the activation energy
• As temperature increases

  The proportion of particles with enough energy to satisfy the activation energy increases
• Catalyst

  Able to decrease the amount of energy needed to break the bonds - activation energy will be lower, and more particles will have enough energy to react making the reaction happen at a faster rate
• Enzymes

  Catalysts that are proteins found in living things, allowing chemical reactions to occur at a fast enough rate at body temperature for the body to function
• Substrate

  The molecule on which an enzyme acts
• Enzymes

  • They will combine with only one particular substrate and be involved in only one specific reaction
  • The enzyme and its substrate have characteristics that are complementary to one another
• Active site

  The part of the enzyme molecule that combines with the substrate
• Enzyme-substrate complex

  When the enzyme and substrate are combined
• Higher concentration of enzyme

  Faster rate of chemical reaction because there are more enzyme molecules to influence reactants
• Increasing substrate concentration

  Increases the rate of the reaction because there will be more substrate molecules coming into contact with the enzyme molecules
• Products of the reaction not continually removed

  Rate of the reaction will slow because it becomes more difficult for the substrate molecules to make contact with the enzyme molecules
• As temperature increases

  Rate of enzyme activity increases
• Beyond 45-50 degrees

  Enzyme structure changes, they are denatured and inactive
• Optimum temperature

  Temperature at which an enzyme works best, typically 30 C to 40 C
• Optimum pH

  pH at which an enzyme will work most effectively
• Cofactors

  Change the shape of the active site so the enzyme can combine with the substrate, without which the enzyme molecule is intact but cannot function
• Coenzymes

  Non-protein organic molecule cofactors, many of which are vitamins
• Enzyme inhibitors

  Substances that slow or stop the enzyme's activity, used by cells to control reactions so products are produced in specific amounts