Enzymes

• What are enzymes?

  Biological catalysts that control reactions in the body
• How specific are enzymes in their function?

  Each enzyme is specific and only works with one substrate
• What factors affect the rate of reaction and activity of enzymes?

  Temperature, substrate concentration, and pH
• What is the optimum pH for the enzyme discussed in the study material?

  6
• What happens to the enzyme's active site when the pH changes?

  It can change shape, affecting its ability to bond with the substrate
• What is the method to investigate the effect of pH on enzyme activity?

  • Add amylase to buffered starch solution
  • Place in a water bath
  • Take samples at regular intervals
  • Use iodine solution to indicate starch presence
  • Repeat at different pH values
• What color does iodine solution turn in the presence of starch?

  Blue/black
• How is the relative rate of reaction calculated for amylase at a specific pH?

  By dividing 1 by the time taken for starch digestion
• If all starch was digested in 20 seconds at pH 6, what is the relative rate of reaction?

  0.05
• What improvements can be made to the method of investigating enzyme activity?

  • Use more accurate measuring apparatus
  • Take the mean of several repeats
  • Measure over a narrower range of pH
• What does the conclusion of the enzyme activity experiment indicate about the enzyme's behavior at different pH levels?

  The rate is high at optimal pH and decreases outside this range
• What is the role of enzymes in digestion?

  To break down large molecules into smaller ones
• Why are enzymes not used up in reactions?

  They can be used over and over again
• What is the importance of breaking down large molecules into smaller ones during digestion?

  Smaller molecules can be absorbed into the blood
• What are the smaller molecules produced from the digestion of large carbohydrates, proteins, and lipids?

  • Carbohydrates → sugars
  • Proteins → amino acids
  • Lipids → fatty acids and glycerol
• Why won't the enzyme that digests lipids digest proteins?

  Because enzymes are specific to their substrates
• Where in a cell would you expect to find enzymes that synthesize amino acids into proteins?

  In the ribosomes