enzymes and enzyme reactions

• Increasing temperature is the only feasible way to speed up chemical reactions in living cells.

  False
• Most chemical reactions in a living cell are naturally quite slow
• What are enzymes sometimes called biological?

  Catalysts
• High temperatures can damage the cells and speed up non-useful reactions
• A catalyst is used up in the reaction it speeds up.

  False
• What is a catalyst defined as?

  Increases reaction speed
• Why is it important that catalysts are not used up in a reaction?

  They can be reused
• What are enzymes made of?

  Amino acids
• The unique shape of an enzyme is determined by its amino acid sequence.
• The region of an enzyme that binds to substrates is called the active site.
• What happens if a substrate does not fit the active site of an enzyme?

  The reaction is not catalyzed
• Describe the steps of the lock and key model of enzyme action.

  1️⃣ The substrate binds to the active site

  2️⃣ The enzyme catalyzes the reaction

  3️⃣ The product is released
• In the induced fit model, the enzyme changes shape slightly to fit the substrate better.
• The lock and key model explains that substrates must fit perfectly into the active site.
• What is the active site complementary to in the induced fit model?

  Substrates
• Match the enzyme models with their key features.

  Lock and key ↔️ Substrate fits perfectly into active site

  Induced fit ↔️ Enzyme changes shape to bind substrate
• What two factors affect the functioning of enzymes as discussed in the video?

  Temperature and pH
• As temperature increases, the rate of an enzyme-controlled reaction initially increases due to higher kinetic energy of particles.
• Enzymes denature at high temperatures because their bonds break, changing the active site's shape.
• All enzymes have the same optimal temperature.

  False
• The temperature at which an enzyme works best is called its optimal temperature.
• At what temperature does the enzyme in the example graph become denatured?

  45°C
• What is pH a measure of?

  Acidity
• Enzymes work best within a specific pH range, and this is called their optimal pH.
• Extreme pH levels can denature enzymes by breaking their bonds and changing the active site's shape.
• Enzymes in the stomach have an optimal pH of around 2 because they function in an acidic environment.
• What is the optimal pH for most enzymes in the human body?

  Around 7