Enzymes

• What is an enzyme?


  A protein that functions as a biological catalyst
• What is the role of an enzyme in a chemical reaction?

  Speeds up the rate of reaction without being used up
• What is the lock and key model?

  A model that explains how an enzyme reacts with its substrate

  
• What is the name of the enzyme that breaks down starch to glucose?

  Amylase
• What is substrate specificity?

  The ability of an enzyme to catalyse only one type of substrate
• How does temperature affect enzyme activity?

  Increasing temperature increases enzyme activity until it reaches the optimum temperature, then denaturation occurs

  
• What is the optimum temperature for most enzymes in the human body?

  Between 35-40°C

  
• What happens to an enzyme when it is denatured?

  The enzyme's structure changes, and it can no longer function

  
• What is the effect of pH on enzyme activity?

  Each enzyme operates best at a particular pH, and a change in pH can denature the enzyme

  
• How does enzyme concentration affect enzyme activity?

  Increasing enzyme concentration increases enzyme activity until all substrate molecules are bound, then activity levels off

  
• What is an inhibitor?

  A molecule that fits into the active site of an enzyme and stops the normal substrate from entering

  
• What are the different types of enzymes that break down carbohydrates, proteins, and lipids?

  • Carbohydrase (breaks down carbohydrates to glucose)
  • Amylase (breaks down starch to glucose)
  • Protease (breaks down proteins to amino acids)
  • Lipase (breaks down lipids to fatty acids and glycerol)
• What are the factors that affect enzyme activity?

  • Temperature
  • pH
  • Enzyme concentration
  • Inhibitors

  
• What happens to enzyme activity when there are more enzyme molecules available?

  Activity increases
• Why does enzyme activity level off at a certain point?

  Not enough substrate molecules

  
• What is the effect of an inhibitor on enzyme activity?

  Reduces rate of reaction
• What are the properties of enzymes?

  • Enzymes are substrate specific
  • Enzymes are catalysts that can be used over again
  • Enzymes are sensitive to heat
  • Enzymes are sensitive to pH
• Why do enzymes react slowly at low temperatures?

  Less kinetic energy
• What is the optimum pH of an enzyme?

  pH for highest rate of reaction

  
• What is denaturation and its effect on enzyme activity?

  Permanent change to active site, reduces reaction rate

  
• What is the method for investigating the effect of temperature on enzyme action?

  1. Set up water baths at various temperatures
  2. Label test tubes with starch and amylase
  3. Measure starch and amylase solutions into test tubes
  4. Place test tubes in water baths for 5 minutes
  5. Add amylase to starch and start timer
  6. Remove samples and add to iodine on spotting tile
  7. Repeat steps 5-6 until iodine no longer changes color
  8. Record results and draw graph
• What is the purpose of placing a tube of amylase and a tube of starch in the water bath for five minutes?

  Allow enzyme and substrate to reach same temperature
• What effect will the sample drop have on the iodine solution at zero minutes?

  Turns blue-black
• Why will the iodine show no color change after a period of time?

  Enzyme breaks down starch to glucose
• Why is it appropriate to use a line of best fit on a graph of these results?

  Allows all points to contribute to identifying optimum temperature

  
• What happens to the starch after 50°C?

  Enzyme is denatured, no breakdown
• What are the main enzymes used in the digestive system?

  • Amylase
  • Protease
  • Lipase
• What is the purpose of thermostable enzymes in biological washing powders?

  Can work at wide range of temperatures
• What are the features of the ileum that aid absorption?

  • Large surface area
  • Thin
  • Permeable
  • Good blood supply
  • Villi
• What is the main function of the ileum?

  Absorption of digested food products
• What are the features of villi that aid absorption?

  • Good blood supply
  • Lacteal
  • Single layer of surface epithelium cells
  • Permeable
• What is digestion?

  Breakdown of large molecules into small molecules

  
• Why are enzymes important in the digestive system?

  Break down large molecules into small molecules for absorption
• What are the roles of amylase, protease, and lipase in the digestive system?

  • Amylase: breaks down starch into glucose
  • Protease: breaks down protein into amino acids
  • Lipase: breaks down fats into fatty acids and glycerol
• How does temperature affect enzyme activity?

  Optimum temperature for maximum activity, denaturation at high temperatures

  
• Why are thermostable enzymes important in commercial applications?

  Can work at wide range of temperatures, saving energy and money