Enzymes and their biological functions test revision

• What is the nature of enzymes?

  Enzymes are proteins.
• What are the general properties of enzymes?

  • Enzymes are biological catalysts.
  • They speed up chemical reactions.
  • They are specific to substrates.
  • They are not consumed in the reaction.
  • They can be regulated by inhibitors and activators.
• Where do enzymes act?

  Enzymes act at specific sites called active sites.
• What is an active site?

  An active site is the region on an enzyme where substrate molecules bind.
• What is the lock-and-key model of enzyme action?

  • The lock-and-key model describes how enzymes and substrates fit together.
  • The enzyme (lock) has a specific shape.
  • The substrate (key) fits perfectly into the active site.
  • This model emphasizes specificity in enzyme-substrate interactions.
• What is the induced fit model in relation to enzymes?

  It describes how enzymes change shape to fit substrates better during a reaction.
• How do enzymes affect activation energy?

  Enzymes lower the activation energy required for a reaction to occur.
• What factors affect enzyme activity?

  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
• What happens to the rate of reaction as substrate concentration increases?

  The rate of reaction increases until it reaches a saturation point.
• What is the saturation point in enzyme reactions?

  The saturation point is when all enzyme molecules are occupied by substrate.
• How does enzyme concentration affect the rate of reaction?

  As enzyme concentration increases, the rate of reaction increases until it plateaus.
• What is enzyme inhibition?

  Enzyme inhibition is the decrease in the rate of an enzyme-catalyzed reaction.
• What is competitive inhibition?

  Competitive inhibition occurs when an inhibitor competes with the substrate for the active site.
• How can the effects of competitive inhibition be reversed?

  By increasing the concentration of the substrate relative to the inhibitor.
• What is non-competitive inhibition?

  Non-competitive inhibition occurs when an inhibitor binds to a site other than the active site.
• What are examples of non-competitive inhibitors?

  Heavy metal ions such as Hg$^{2+}$, Pb$^{2+}$, and As$^{3+}$.
• What is enzyme immobilisation?

  • Enzymes are attached to an inert, insoluble material.
  • Allows enzymes to be reused multiple times.
  • Makes the process more economically viable.
• What is the benefit of immobilising enzymes in industrial processes?

  It allows enzymes to be reused, reducing costs and waste.
• What are some industrial applications of immobilised enzymes?

  • Production of antibiotics
  • Synthesis of semi-synthetic penicillins
  • Production of high-fructose corn syrup
  • Conversion of lactose to glucose and galactose in the dairy industry
• What are the methods of enzyme immobilisation?

  • Adsorption: Enzymes bind to an inert surface.
  • Covalent binding: Enzymes are covalently bonded to a solid support.
  • Entrapment: Enzymes are physically trapped within a support matrix.
• What is the drawback of the adsorption method for enzyme immobilisation?

  Enzymes may leach from the surface, decreasing their activity.
• What is a disadvantage of covalent binding for enzyme immobilisation?

  The harsh conditions required can damage the enzyme's active site.
• Why is entrapment often the most successful method of enzyme immobilisation?

  It protects enzymes from harsh conditions, preserving their activity.
• How does enzyme concentration affect reaction rates?

  • High enzyme concentrations can speed up reactions.
  • Immobilised enzymes are more efficient at higher concentrations.
• What does the graph showing reaction rate changes with enzyme concentration indicate?

  It shows that immobilised enzymes are more efficient at higher concentrations.