1.2.1 Enzyme Function

• Enzymes are biological catalysts that speed up chemical reactions
• Enzymes work by lowering the activation energy
• What does the lock-and-key model explain about enzyme action?

  Substrate-active site binding
• Enzymes work by lowering the activation energy needed for a reaction to occur.
• What is the region of an enzyme where the substrate binds?

  Active site
• The induced fit model suggests that the active site of an enzyme is flexible.
• What is the effect of competitive inhibitors on enzyme activity?

  Reduce V_max
• What do enzymes do in living organisms?

  Speed up chemical reactions
• Steps of enzyme action

  1️⃣ Enzyme binds to substrate

  2️⃣ Substrate is converted into product

  3️⃣ Enzyme is released unchanged
• What does the lock-and-key model describe about enzyme-substrate binding?

  Rigid, complementary fit
• Match the type of inhibitor with its effect:

  Competitive inhibitor ↔️ Prevents substrate binding

  Non-competitive inhibitor ↔️ Reduces enzyme efficiency
• Enzymes are produced by living organisms.


  True
• The active site of an enzyme has a structure complementary to the substrate.

  True
• The enzyme amylase breaks down starch into glucose
• Enzymes are not consumed or changed during a reaction.
• What does the lock-and-key model suggest about the shapes of the active site and the substrate?

  Complementary
• What happens to enzyme activity at extreme pH levels?

  It decreases
• Enzymes are biological catalysts
• Enzymes lower the activation energy
• The induced fit model suggests the active site is rigid.

  False
• Extreme temperatures can denature enzymes.

  True
• Which enzyme is used in detergent manufacturing to break down proteins?

  Proteases
• What is one characteristic that distinguishes enzymes from other catalysts?

  Highly specific to substrates
• What happens to enzymes after they catalyze a reaction?

  They remain unchanged
• Steps involved in the lock-and-key model of enzyme action

  1️⃣ The substrate binds to the active site

  2️⃣ The enzyme catalyzes the reaction

  3️⃣ The products are released
• Enzymes are highly specific to their substrates.


  True
• The binding of a substrate to the active site follows the lock-and-key model.
• High temperatures can denature enzymes.


  True
• Non-competitive inhibitors bind to a site other than the active site of the enzyme.
• Enzymes are less specific than synthetic catalysts.

  False
• Match the enzyme feature with its description:

  Active site ↔️ Region where substrate binds

  Complementary structure ↔️ Ensures precise substrate binding
• The induced fit model suggests the active site is flexible
• Amylases are used in food production to hydrolyze starch