A LEVEL BIOLOGY [OCR]: ENZYMES

• What is the lock and key hypothesis?

  The idea that the enzyme has a fixed shape and only the right substrate will fit into the active site
• What is the induced fit hypothesis?

  The idea that the enzyme changes shape as the substrate enters.
• What is an enzyme?

  Globular proteins that are biological catalysts and can either be intracellular or extracellular
• What is a metabolic pathway?

  A series of reactions that are catalyzed by different enzymes and result in one or more products
• What factors affect enzymes?

  • temperature• pH• enzyme concentratiom• substrate concentration
• What happens at sub-optimum temperature in terms of it's effect on enzymes?

  The rise in temperature increases the kinetic energy of the reactants.
• What happens to enzymes below optimum temperature?

  Molecules in culture have little kinetic energy and collisions between enzymes are rare so there is a low rate of reaction
• What happens to enzymes at optimum temperature?

  Molecules in culture have kinetic energy and there are many collisons so the maximum rate of reaction is achieved
• What happens to enzymes above optimum temperature?

  Molecules have more kinetic energy and collisions are frequent but the tertiary structure is altered so the active sight loses its complimentary shape and reaction stops.
• What happens to enzymes if the pH is above or below optimum?

  The enzymes denature
• What is a limiting factor?

  A factor which will increase the rate of reaction if all other factors are kept the same aside from thr one which increases also.
• What is anabolism?

  The building up of a reaction
• What is catabolism?


  The breaking down of a reaction
• What is metabolism?

  The chemical processes that occur in a living organism which can be seperated into anabolism and catabolism.
• What are specific biological catalysts?

  They catalyse only specific reactions
• What is the enzymes for:• lactose • atp• lipids • proteins

  Lactose — lactaseAtp — atpase Lipids — lipaseProteins — protease
• An enzyme and substrate is needed for a reaction to occur but what else is needed?

  Amino acids
• What is a cofactors?


  A non-protein substance that is necessary for an enzyme controlled reaction to take place
• What are the three main types of co factor?

  Prosthetic groupsInorganic ion cofactors Coenzymes
• What is a prosthetic group?


  Groups that are permanently bound to the enzyme
• What is a inorganic ion cofactors?

  A group that is temporarily bound to the enzyme
• What is a co enzyme?

  Inorganic molecules that bind temporarily to the enzyme
• What is a competitive inhibitor?


  A molecule with a similar shape to the subtrate that blocks the active site so the subtrate cannot bind to it until that molecule is gone which slows down the rate of reaction.
• What is a non-competitive inhibitor?

  A molecule that fits in the enzyme at the allestoric site then changes the shape of the enzyme so it is not complementary to the subtrate and slows down the reaction.
• What is end-product inhibition?

  The end product of a reaction acts as a regulator in a process called end product inhibition. This is the process when if the end products amount is too high, then it binds non-competitively with an enzyme so there's no further production of that product.If the end product amount falls then inhibition ends snd the product restarts