Enzymes

• What are enzymes described as in the study material?

  Substances on the margins of the protein world that make reactions happen faster without being changed themselves
• What is the role of enzymes in cell reactions?

  • Enzymes control thousands of different chemical reactions inside cells
  • They ensure reactions are ordered and controlled for proper functioning
  • They speed up reactions without being changed or used up
• How does temperature affect enzyme reactions?

  Raising the temperature usually speeds up reactions but can also cause unwanted reactions and potential cell damage
• What do enzymes reduce the need for?

  High temperatures
• What is unique about each biological reaction in terms of enzymes?

  Every different biological reaction has its own specific enzyme
• What is the active site of an enzyme?

  The part of the enzyme that locks onto its substrate to catalyze the reaction
• What does high specificity mean in relation to enzymes?

  Enzymes usually only work with one substrate
• What is the lock and key hypothesis?

  The substrate fits into the enzyme's active site like a key fits into a lock
• What happens to an enzyme when it becomes denatured?

  It loses its shape and the substrate can’t fit into the active site anymore
• What is the optimum temperature for most important human enzymes?

  About 37˚C
• How does pH affect enzyme activity?

  If the pH is too high or too low, it can interfere with the bonds holding the enzyme together, changing the shape of the active site
• What is the optimum pH for pepsin?

  pH 2
• How does enzyme concentration affect the rate of reaction?

  • More enzyme molecules increase the likelihood of substrate molecules meeting and reacting
  • Increasing enzyme concentration raises the rate of reaction until substrate is limited
• How does substrate concentration affect the rate of reaction?

  • Higher substrate concentration increases the reaction rate
  • This is true only up to a point; after that, all active sites are full and adding more substrate makes no difference
• What is a practical way to investigate how temperature affects enzyme activity?

  1. Set up a reaction at different temperatures (e.g., 10°C, 20°C, 30°C, 40°C)
  2. Measure the amount of product produced over time
  3. Calculate the rate of reaction for each temperature
• How can you measure how fast a substrate disappears in an enzyme reaction?

  1. Use iodine solution to test for starch presence
  2. Take samples at regular intervals and observe color change
  3. Record the total time taken for starch to disappear
• What is the importance of controlling variables in enzyme experiments?

  • To ensure that only the variable being tested affects the results
  • To obtain reliable and valid data