Biology unit 1.4

• What is the role of enzymes in metabolic reactions?

  Biological catalysts that speed up reactions
• What happens in reactions where larger molecules are broken down by enzymes?

  Larger molecules become smaller molecules
• What happens in reactions where smaller molecules are built up into larger, more complex, molecules by enzymes?

  Smaller molecules become larger molecules
• What is the molecule that an enzyme reacts with called?

  A substrate
• What is the specific area on an enzyme where substrate molecules bind?

  The active site
• What two things are combined together to form an enzyme?

  Protein and core
• What kind of enzymes build larger products from smaller substrate molecules?

  Anabolic enzymes
• What kind of enzymes break large substrate molecules into smaller products?

  Catabolic enzymes
• In the reaction enzyme + substrate = enzyme-substrate complex = enzyme-product complex = enzyme + product, what does the enzyme do?

  The enzyme is released unchanged
• Where is the enzyme lysozyme found?

  Tears and other secretions
• What is the function of lysozyme?

  To destroy pathogenic bacteria
• How does lysozyme destroy bacterial cell walls?

  By breaking glycosidic bonds
• What is the bacterial cell wall made of?

  Polysaccharide of amino sugars
• How many amino sugars long is the section of polysaccharide that fits into the groove on lysozyme?

  Six
• What types of bonds hold the substrate in place in the lysozyme molecule?

  Hydrogen and ionic bonds
• What type of reaction is the breakdown of polysaccharide by lysozyme?

  Catabolic
• What is the relationship between the shape of the substrate and the active site of the enzyme?

  Complementary
• According to collision theory, what must occur for molecules to react?

  Molecules must collide
• According to collision theory, what must a collision have to produce a reaction?

  Enough energy and correct orientation
• What determines the rate of reaction, according to collision theory?

  Rate of successful collisions
• What is the energy required for a successful collision called?

  Activation energy
• According to the induced fit model, what does the enzyme do to accommodate the substrate?

  Changes shape slightly
• According to the induced fit model, what does the enzyme change do to the substrate molecule?

  Places a strain and distorts it
• According to the induced fit model, what does distortion of a bond do to the activation energy?

  Lowers it
• How does distorting the substrate molecule affect its potential energy?

  Reduces its potential energy
• After the reaction occurs, what happens to the products in relation to the active site?

  They no longer bind to it
• What does it mean for an enzyme to be specific?

  Catalyzes only one reaction
• What is a key feature of enzymes regarding their activity?

  They are very efficient
• What do enzymes do to the activation energy of a reaction in the body?

  Lower it
• How do enzymes allow reactions to take place in the body?

  At lower temperatures
• In an enzyme-controlled reaction, how can the reaction's progress be followed?

  By measuring product or substrate
• In an enzyme-controlled reaction, when are there a large number of substrate molecules available?

  When enzyme and substrate are mixed
• During an enzyme-controlled reaction, what comes into contact with the empty active sites of the enzyme?

  Substrate molecules
• During an enzyme-controlled reaction, what happens when all active sites become filled?

  They rapidly break down to products
• How does the amount of substrate change as an enzyme-controlled reaction proceeds?

  It decreases
• How does the amount of product change as an enzyme-controlled reaction proceeds?

  It increases
• Why does the graph of an enzyme-catalyzed reaction flatten out in due course?

  All substrate has been used up
• What are three factors that can affect enzyme activity?

  • Temperature
  • Substrate concentration
  • Enzyme concentration
• How does an increase in temperature affect the kinetic energy of molecules in an enzyme-controlled reaction?

  It increases it
• What does increased kinetic energy lead to in an enzyme-controlled reaction?

  More successful collisions