Enzymes

• What are enzymes?

  Enzymes are biological catalysts. They catalyse/speed up the rate of chemical reaction within a cell. They are proteins made by living cells.
• What are always enzymes involved in?

  Metabolic reactions
• What do enzymes do?

  The build up large molecules from small molecules and break down large molecules into small ones
• Name an example of an enzyme breaking down molecules

  Respiration/digestion
• Name an example of an enzyme building up molecules

  Protein synthesis
• Forming an enzyme


  The amino acids are in sequence in a chain. The sequence of the amino acids determines the shape of the enzyme and its active site meaning it also determines it's use
• What is the lock and key theory?

  The idea that a substrate and enzyme collide perfectly like a key in a lock to form a reaction.
• Lock and key theory products

  • Enzyme is the lock
  • Substrate is the key
  • Forms an enzyme substrate complex
• Lock and key theory stages

  Stage 1 - The substrate collides with the active site

  Stage 2 - The enzyme catalyses the break down of the substrate

  Stage 3 - The products are released from the active site.
• Optimum temperature/pH

  Temperature/pH of which an enzyme is working at it's fastest rate
• Enzymes at low temperature


  Low kinetic energy. Not many successful collision. Little products. Doesn't change shape.
• Enzymes at optimum temperature


  Higher kinetic energy. Many successful collision. More product.
• Enzymes at high temperature


  Active site is denatured. Less successful collisions. No product
• Enzymes at optimum pH

  Rate of reaction is highest. Each substrate fits into the enzyme perfectly.
• Enzymes near optimum pH


  Active site is changing making it harder for particles to to attach.
• Enzymes at extreme pH


  Reaction stops. The enzyme denatures.