Enzymes

• What is the induced fit model of enzyme action ?

  • Improved model that scientists proposed
• The active site of an enzyme has a shape complementary to its substrate.
• What is the lock and key model of enzyme action ?

  First model that scientists proposed

  • Thought that in order for an enzyme to catalyse a reaction ; the substrate had to fit perfectly into the active site.
• What is the name of the special region of an enzyme that binds to the substrate ?

  Active site
• What is a catalyst ?

  A substance that increases the rate of a chemical reaction without being consumed in the process.
• What do we call the complex that is formed when an enzyme binds to a substrate ?

  Enzyme - substrate complex
• What is an enzyme ?

  Biological catalysts that are responsible for speeding up chemical reactions
• The rate of chemical reactions increases with temperature.

  Why don’t we increase the temperature of our cells to increase the rate of chemical reactions

  • Heating our cells would require a lot of energy
  • Higher temperatures could damage our cells
  • Higher temperatures would also speed up non-useful reactions
• What is a catalyst

  A substance that increases the speed of a chemical reaction without being used up or changed in the process
• Why do organisms need enzymes

  Most chemical reactions are really slow
• What is pH

  A measure of hydrogen ion concentration or a measure of acidity
• What is the optimum temperature of enzymes in the human body ?

  37 - 38 ° C
• What does the term ‘optimum‘ mean for enzyme temperature

  The temperature that gives the highest enzyme activity
• Explain how high or low pH can cause an enzyme to denature

  • High or low pH can break the bonds holding the enzyme together
  • This causes the enzyme and its active site to change
  • So enzyme is no longer complementary to the substrate
  • So it can no longer form an enzyme - substrate complex
• What are the 2 main factors that affect enzyme activity ?

  1. Temperature
  2. pH