Internal membranes and enzymes

• The folding of membrane in the mitochondria increases the surface area for enzyme-controlled reactions
• The active site of an enzyme is where the substrate binds
• enzymes: biological catalysts that reduce the activation energy for a reaction, they cannot be used up
• An example of enzyme and substrate: starch (substrate), and amylase (enzyme) which breaks the substrate down to make glucose
• Catabolic reactions: larger molecules broken down
• Anabolic reactions: smaller molecules forming larger ones
• Activation energy: energy needed to initiate a chemical reaction
• Enzymes reduce the activation energy by binding to the active site of the substrate and holding them in a way that allows catabolic or anabolic reactions to occur more readily
• induced fit model: the active site of an enzyme changes shape to fit the substrate
• lock and key model: enzymes are specific to substrate, substrate fits into active site
• Factors affecting enzyme reaction rates:

  1. temperature
  2. pH
  3. substrate concentration
  4. cofactors (some enzymes require them to be attached to create a binding site for activation)
  5. inhibitors (compete for space in the binding site)