enzymes

• what are enzymes?


  biological catalysts that speed up metabolic reactions.
• what are enzymes made of and what does this mean?

  enzymes are made of proteins meaning they have their own specific 3D shape based on their tertiary structure.enzymes are highly specific (each metabolic reaction has its own enzyme to catalyse it
• what is the enzymes specificity?

  • active sight is specific and unique in shape because of the specific folding and bonding in the tertiary structure.
  • this ensures the active site is complementary to 1 specificsubstrate.
• what is an enzymes structure?

  1. substrate- substance on which the enzyme acts

  2) active site- where the substrate attaches

  3) enzyme- biological catalyst.
• what does an enzyme do to activation energy?

  it lowers activation energy by bending and weakening bonds and splitting the reaction into little steps.
• what is the lock and key hypothesis?

  -the active site is exactly complementary to the substrate.-the active site is a fixed shape-due to random collisions the substrate can collide and attach to the enzyme-this forms an enzyme substrate complex.
• what is the induced fit hypothesis?

  -this is when the active site slightly changes shape to mouldaround the substrate. this puts strain on the bonds andtherefore lowers activation energy.function

  • the induced fit model is the accepted model for enzymes
• what are competitive inhibitors?

  -has a similar shape to the substrate and competes for the active site.-forms an enzyme inhibitor complex-prevents an enzyme substrate complex forming-slows rate of reaction
• what are non-competitive inhibitors?

  -different in shape to substrate-binds to allosteric site not the active site-as it binds it forms a conformational change in the tertiary structure of the enzyme including the active site.-substrate can no longer bind to active site so no es complexes formed-reaction rate slows
• how and why does temperature effect rate of enzyme reaction?

  rate of reaction increases as temperature increases because there is more kinetic energy which means there are more collisions between enzymes and substrates which equal more es complexes.however when optimum temperature is reached the enzyme denatures and rate of reaction falls. this is because high temperatures disrupt H and ionic bonds so the enzymes tertiary structure changes.
• how and why does ph effect enzyme rate of reaction?

  as ph increases so does rate of reaction. this happens until optimum ph is reached and rate of reaction falls.this happens because above and below optimum temperature h and ionic bonds are disrupted leading to the tertiary structure being altered. the enzyme then denatures so there is no es complexes
• how and why does substrate concentration effect enzyme rate of reaction?

  as substrate concentration increases so does rate of reaction because there is more collisions which leads to more es complexes. however active sites become saturated quicker which means that there is no further increase in the rate of reaction and the graph/results plateaus.
• how and why does enzyme concentration effect enzyme rate of reaction?

  the more enzyme molecules, the more likely collisions between enzymes and substrates will happen to form an enzyme substrate complex. therefore increasing enzyme concentration increases rate of reaction.

  however if there is limited numbers of substrate there will be a time when the enzyme concentration will have no effect as there is more than enough enzymes to deal with the substrates