Enzymes

• What do you need to know about enzymes and how they work?

  You need to understand their specificity, role in cellular reactions, mechanism of action, activation energy reduction, and effects of various factors on enzyme activity.
• What defines the specificity of an enzyme?

  Enzymes are highly specific and are involved in only one reaction type.
• What types of biochemical reactions in cells are controlled by enzymes?

  Catabolic reactions and anabolic reactions.
• What is a catabolic reaction?

  A catabolic reaction is when large molecules are broken down into smaller subunits, such as in the digestion of nutrients.
• What is an anabolic reaction?

  An anabolic reaction is when smaller subunits are used to build up larger molecules, such as when the body makes proteins.
• What does an enzyme lower to allow reactions to occur?

  Activation energy.
• Why do enzymes allow reactions to occur?

  Because they lower the activation energy necessary to start a reaction.
• What are the reactants and products in an enzyme-catalyzed reaction?

  • Reactants: The starting materials of the reaction
  • Products: The resulting molecules after the reaction
• What energy factors are involved in enzyme-controlled reactions?

  • Energy of reactants
  • Activation energy
  • Energy of products
• What measures the time in enzyme-controlled reactions?

  • Time of reaction onset
  • Time to reach maximum reaction rate
  • Total reaction time
• Why is less energy needed to start a reaction when an enzyme is present?

  Because enzymes lower the activation energy, reducing the minimum energy required to start the reaction.
• How do enzymes speed up the rate of a reaction?

  They lower the activation energy necessary to start the reaction.
• Why is the structure of enzymes important?

  Their globular protein structure with a compact 3D shape and specific active sites are crucial for enzyme specificity and catalytic function.
• What types of bonds maintain the structure of enzymes?

  Hydrogen bonds, disulphide bridges, and ionic bonds.
• What is the active site of an enzyme?

  The active site is the region on the enzyme molecule where the reaction takes place.
• How does the active site contribute to enzyme specificity?

  The active site may have a precise shape that only allows certain substrates to combine, giving the enzyme specificity.
• How do enzymes work?

  Enzymes bind substrates at the active site, forming an enzyme-substrate complex, catalyze the reaction, and release the products unchanged.
• What is an enzyme-substrate complex?

  An enzyme-substrate complex is formed when the enzyme and substrate are in contact with each other.
• What are the main components of enzyme structure and mode of action?

  • Enzyme structure: Tertiary structure held by bonds, globular shape, precise active site
  • Mode of action: Substrate binding at active site, enzyme-substrate complex formation, reaction catalysis, product release, enzyme remains unchanged
• What is the role of enzymes in biological systems?

  They act as biological catalysts and are involved in a wide variety of reactions.
• In what variety of reactions are enzymes involved?

  A wide variety of reactions.
• What is the chemical composition of enzymes?

  All enzymes are proteins.
• Why is the tertiary structure of enzymes important?

  It provides the specific tertiary structure necessary for the reaction they control by providing specificity.
• What does the specific tertiary structure of an enzyme determine?

  Enzyme specificity.
• What is the basic role of enzymes in cells?

  They catalyze and speed up reactions in cells.
• What would happen in cells without enzymes?

  Reactions would occur very slowly, or may not occur at all.
• What are enzymes made up of?

  Enzymes are made up of proteins.
• How many different types of enzymes are there in living organisms?

  Many different types.
• What type of proteins are enzymes?

  Enzymes are globular proteins.
• What structure defines an enzyme's specificity?

  Their precise tertiary structure.
• What are the two models for enzyme action?

  • Lock and key model
  • Induced fit model
• What does the lock and key model propose?

  The active site and the substrate are complementary, with the substrate fitting the active site like a key fits a lock.
• What does the induced fit model suggest?

  The active site is very similar to the substrate, and when the substrate binds, it molds around the substrate, putting it under strain to facilitate the reaction.
• What are the main components of an enzyme?

  Enzymes are made up of proteins.
• How does the enzyme change shape when the substrate binds?

  The enzyme changes its shape slightly to accommodate the substrate.
• What is an enzyme-products complex?

  It's the complex formed after the enzyme has catalyzed the reaction and products are bound to the enzyme.
• What happens after the enzyme-products complex is formed?

  The products leave the active site of the enzyme.
• What is released after the reaction is catalyzed?

  Products are released from the active site of the enzyme.
• Summarize the induced fit model for enzyme action.

  The active site is flexible and changes shape when a substrate binds. This strain on the substrate facilitates the reaction, after which the enzyme returns to its original shape.
• What factors affect enzyme activity?

  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
  • Inhibitors