A-level Biology - Module 2 - Enzymes

• What are enzymes classified as?

  Biological catalysts
• What is the primary function of enzymes?

  To lower the activation energy of reactions
• What type of structure do enzymes have?

  Complicated 3D structure, either tertiary or quaternary
• How do enzymes affect the rate of reaction?

  They speed up the rate of reaction
• What is the symbol for activation energy?

  EA
• What is the difference between uncatalyzed and catalyzed activation energy?

  Catalyzed activation energy is lower than uncatalyzed activation energy
• What type of reaction is represented when a molecule is split into two?

  Hydrolysis reaction
• What does an exothermic reaction indicate about energy?

  Energy is being released
• How much can enzymes speed up reactions?

  Up to ten to twelve trillion times
• What are the two models of enzyme action?

  • Lock and key model
  • Induced fit model
• What happens in the lock and key model of enzyme action?

  The enzyme is already the perfect shape to fit the substrates
• What occurs in the induced fit model of enzyme action?

  There is a subtle change of shape in the enzyme when substrates bind
• What is an example of an intracellular enzyme?

  Catalase
• What does catalase do?

  It breaks down hydrogen peroxide into water and oxygen
• What is an example of an extracellular enzyme?

  Pepsin
• Where is pepsin produced?

  In the stomach
• What are cofactors?

  Non-protein substances required for enzyme activity
• What are the two types of cofactors?

  Prosthetic groups and coenzymes
• What is a prosthetic group?

  A tightly bound cofactor that is always present
• What is a coenzyme?

  A temporary cofactor that binds just before the enzyme works
• What are two examples of ions that act as coenzymes?

  Zinc and chlorine
• What are anabolic reactions?

  Reactions that build things by joining molecules together
• What are catabolic reactions?

  Reactions that break or split molecules apart
• What is the optimum temperature for most enzymes?

  37 degrees Celsius
• What does an increase in temperature do to enzyme activity?

  It increases particle movement and the formation of enzyme-substrate complexes
• What is the significance of the shape of the temperature effect graph for enzymes?

  It shows the relationship between temperature and enzyme activity
• What happens to enzyme activity at temperatures above the optimum?

  Enzyme activity typically decreases due to denaturation
• What is the role of substrate concentration in enzyme activity?

  Higher substrate concentration increases the rate of reaction until saturation
• What effect do inhibitors have on enzyme activity?

  Inhibitors decrease the rate of enzyme activity
• What is the relationship between enzyme concentration and reaction rate?

  Higher enzyme concentration increases the rate of reaction
• What is the significance of enzyme-substrate complexes?

  They are essential for the reaction to occur
• How do enzymes contribute to metabolic processes?

  They facilitate biochemical reactions necessary for life
• What is the effect of pH on enzyme activity?

  Each enzyme has an optimum pH at which it functions best
• What happens to enzymes at extreme pH levels?

  They can denature and lose their activity
• What is the role of temperature in enzyme activity?

  Temperature affects the kinetic energy of molecules and enzyme activity
• How do enzymes interact with substrates?

  They bind to substrates at the active site to form enzyme-substrate complexes
• What is the importance of enzyme specificity?

  Enzymes are specific to their substrates, ensuring precise biochemical reactions
• What is the effect of competitive inhibitors on enzyme activity?

  They compete with substrates for the active site, reducing enzyme activity
• What is the effect of non-competitive inhibitors on enzyme activity?

  They bind to an enzyme at a site other than the active site, reducing activity
• How can enzyme activity be measured?

  By measuring the rate of product formation or substrate consumption