3.2 Enzyme Catalysis

• Enzymes speed up chemical reactions in living organisms by binding to and stabilizing the transition state
• Match the reaction type with its characteristics:

  Catalyzed ↔️ Lower activation energy

  Uncatalyzed ↔️ Higher activation energy
• Enzymes interact with a single type of substrate.


  True
• Arrange the following reaction types based on their activation energy levels from highest to lowest:

  1️⃣ Uncatalyzed

  2️⃣ Catalyzed
• What gives enzymes their high specificity for particular substrates?

  Their 3D shape
• Match the enzyme binding model with its description:

  Lock-and-Key ↔️ Rigid active site

  Induced-Fit ↔️ Flexible active site
• The lock-and-key model proposes that the enzyme has a rigid active site that exactly fits the substrate
• What role do enzymes play in biological processes?

  Biological catalysts
• Steps in enzyme-catalyzed reactions

  1️⃣ Enzyme binds to substrate

  2️⃣ Enzyme stabilizes the transition state

  3️⃣ Reaction occurs

  4️⃣ Product is released
• What is the key difference between the lock-and-key and induced-fit models of enzyme binding?

  Active site flexibility
• What is the primary role of enzymes in enzyme catalysis?

  Lower activation energy
• The lock-and-key model proposes that the enzyme's active site is rigid
• How do enzymes lower the activation energy of a reaction?

  By stabilizing the transition state
• Order the steps of how temperature affects enzyme activity:

  1️⃣ Enzyme activity increases with temperature

  2️⃣ Optimal temperature is reached

  3️⃣ Further increase in temperature denatures the enzyme
• Increasing substrate concentration always increases enzyme activity.

  False
• Enzymes can have regulatory binding sites separate from their active site in a process called allosteric regulation
• What is the effect of phosphorylation on enzyme activity?

  It can activate or inhibit
• Enzymes can be sequestered in specific cellular compartments
• What are enzymes defined as?

  Biological catalysts
• Enzymes lower the activation energy needed for reactions to occur.


  True
• What is one key benefit of enzymes in biological reactions?

  Accelerated reactions
• Enzymes lower the activation energy required for chemical reactions, allowing them to occur more easily
• Enzymes enable reactions to occur under optimal conditions.


  True
• Enzymes lower the activation energy required for a reaction to occur, enabling it to proceed more easily
• The induced-fit model suggests that the enzyme's active site changes shape upon substrate binding.


  True
• Enzymes increase the rate of a reaction by lowering the activation energy.

  True
• Enzymes exhibit high specificity, meaning each enzyme interacts specifically with a particular substrate
• The 3D shape of an enzyme determines its specificity for a substrate.


  True
• The induced-fit model suggests that the active site of an enzyme is flexible and adjusts its shape upon substrate binding
• What are the two main models that describe enzyme-substrate binding?

  Lock-and-key and induced-fit
• The induced-fit model suggests that the enzyme's active site changes shape upon substrate binding.


  True
• Match the enzyme binding model with its description:

  Lock-and-Key ↔️ Rigid, pre-shaped active site

  Induced-Fit ↔️ Flexible active site that molds
• What happens to enzyme activity if the pH deviates from its optimal range?

  It reduces enzyme activity
• How do inhibitors affect enzyme activity?

  By blocking active sites
• Covalent modification of enzymes always activates their catalytic activity.

  False
• What is the effect of acetylation on enzyme activity?

  It often inhibits
• Order the regulatory mechanisms of enzymes:

  1️⃣ Allosteric regulation

  2️⃣ Covalent modification

  3️⃣ Compartmentalization