enzymes

• what is metabolism

  all of the reactions in the body occur in metabolic pathways
• what are anabolic reactions

  building molecules eg. protein synthesis
• what is a catabolic reaction

  breaking molecules down eg. digestion
• what does endergoic mean

  to take in
• what does exogoic mean

  to give out
• properties of enzymes

  • globular so are soluble
  • catalysts
  • aren't used up or changed in the reaction
  • have a high turn-over number
• what are the three sites of enzyme action

  1. extracellular
  2. intracellular- in solution
  3. intracellular- membrane bound
• what is extracellular site action

  enzymes are secreted by exocytosis eg. amylase in saliva
• what is intracellular-solution site action

  act in a solution inside cells eg maltase
• what is intracellular - membrane bound site action

  attached to membranes like on cristae of mitochondria
• what is the two types e-s complex models

  1. lock and key
  2. induced fit
• explain lock and key model

  the unique shape of the active site is exactly complementary to the active site of the substrate.
• explain the induced fit model

  the enzyme active site is altered to accommodate the substrate
• factors that effect enzyme action

  • temperature
  • ph
  • enzyme concentration
  • substrate concentration
• why do enzymes denature past optimum

  whole molecule vibrates and hydrogen bonds break, altering the tertiary structure so the active site is no longer complementary to substrate
• why does extreme ph. denature enzymes

  both extremes denature the enzymes by the changes to the amino acid side chains on active site. so in acids h+ are added or alkali oh- neutralise so no bonds can be made to attach substrate
• what does a buffer do

  maintains a constant ph by avoiding fluctuations
• what is enzyme inhibition

  the decrease in rate of an enzyme controlled reaction by another molecule binding to the enzyme
• explain competitive inhibition

  inhibitor has similar shape to active site so prevents an enzyme substrate complex from occurring. can be overcome by increasing the substrate concentration.
• explain non-competitive inhibition

  inhibitor binds to the allosteric site causing a conformational change in the active site, so substrate cant bind to the enzyme. cant be overcome by increasing substrate concentration.
• what are immobilised enzymes

  a way of trapping enzymes or binding them to an inert matrix which makes them easier to recover and reuse at the end of the reaction
• ways of immobilising enzymes

  • covalent bonding
  • absorption
  • encapsulation
  • cross-linking
• what are the advantages of immobilising enzymes

  • products not contaminated with the enzyme
  • they are easily recovered for reuse
  • increased stability over high temperatures and ph
  • more than one enzyme can be used
  • they can be added/removed so higher control