Enzymes

• What are enzymes classified as?

  Biological catalysts
• What is the function of enzymes?

  They speed up reactions
• What does the lock and key hypothesis model?

  The specificity of enzymes for their substrate
• What happens to enzymes at extremes of temperature and pH?

  They are denatured
• What are the key characteristics of enzymes?

  • Enzymes are biological catalysts.
  • They are specific for their substrate.
  • They can be denatured by extreme conditions.
  • They speed up chemical reactions without being changed.
• What are enzymes made up of?

  Amino acid molecules
• Why are proteins important for the body?

  They are needed for cell growth and repair
• What is the definition of a catalyst?

  A substance that changes the rate of a chemical reaction without being changed by the reaction itself
• What is the active site of an enzyme?

  The part of the enzyme to which a specific substrate can attach
• How does the lock and key hypothesis explain enzyme specificity?

  The shape of the active site matches the shape of its substrate molecules
• What happens to the enzyme's active site when it is denatured?

  The shape of the active site changes, preventing substrate binding
• What term is used to describe enzymes that have been altered by extreme conditions?

  Denatured
• Why is it important to use the term 'denatured' instead of 'killed' when referring to enzymes?

  Because enzymes have never been alive
• What are the effects of pH and temperature on enzyme activity?

  • Extreme pH can denature enzymes.
  • High temperatures can denature enzymes.
  • Optimal conditions allow enzymes to function effectively.
• What are enzymes classified as?

  Biological catalysts
• How do enzymes interact with their substrates?

  They are specific for their substrate
• What does the lock and key hypothesis model?

  The specificity of enzymes for their substrates
• What happens to enzymes at extremes of temperature and pH?

  They become denatured
• What factors affect the reaction rate of enzymes?

  • Temperature
  • pH
  • Substrate concentration
• How is the rate of an enzyme-catalysed reaction calculated?

  By measuring the rate at which a substrate is used up or a product is formed
• What happens to the rate of an enzyme-catalysed reaction as temperature increases?

  The rate increases until a certain point
• What occurs at high temperatures regarding enzyme activity?

  The rate decreases because the enzyme becomes denatured
• What is the optimum temperature for enzyme activity?

  The temperature at which the enzyme works best
• What is the active site of an enzyme?

  The part of the enzyme to which a specific substrate can attach
• How does pH affect enzyme activity?

  Changes in pH alter the shape of an enzyme’s active site
• What is the pH scale?

  A scale that measures acidity or alkalinity
• What is the optimum pH for enzymes in the small intestine?

  About 7.5
• What happens to enzyme activity as pH increases beyond the optimum?

  There is a sharp decrease in activity as the enzyme’s active site changes shape
• How does substrate concentration affect enzyme activity?

  Enzyme activity increases with substrate concentration until saturation is reached
• What is substrate concentration?

  The amount of a substance dissolved in water
• What occurs when enzymes become saturated with substrate?

  No more substrates can fit at any one time
• What is the optimum substrate concentration for enzyme activity?

  The concentration at which the enzyme works best
• What happens if substrate concentration continues to increase beyond the optimum?

  Enzyme activity remains the same due to insufficient enzyme molecules
• What are enzymes?

  Biological catalysts that speed up reactions.
• What does the lock and key hypothesis model in relation to enzymes?

  It models the specificity of enzymes for their substrate.
• At what conditions are enzymes denatured?

  At extremes of temperature and pH.
• What are the three main food groups mentioned in the study material?

  • Carbohydrates
  • Proteins
  • Lipids
• Why are carbohydrates vital for humans?

  They provide energy and are stored as fat if eaten in excess.
• What role do carbohydrates play in plants?

  They are important for photosynthesis.
• What is the basic building block of carbohydrates?

  A monosaccharide.