enzymes
- Created by: kierasanghera
- Created on: 23-05-16 08:32
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- Enzymes
- competitive inhibitors
- binds to the active site
- prevents the substrate from binding
- slows down rate of reaction
- effect is often reversible
- e.g the use of ethanol foranti freeze
- if taken into the body the liver breaks it down into alcohol dehydrogenase which in the liver breaks down to oxalic acid
- the ethanol competitively inhibits alcohol dehydrogenase so that less oxalic acid is formed
- non competitive inhibitors
- binds to the alllosteric site on the enzyme
- changes the shape of the active site
- prevents the substrate from binding
- effect is often irreversable
- e.g potassium cyanide
- inhibits cell respiration
- non competitive inhibitor for the enzyme cytochrome oxidase
- ATP cannot be made
- organism respires anaerobically so lactic acid builds up in the blood
- coenzymes
- organic non protein molecules
- bind either just before or at the same time as the substrate
- may take part in the reaction but are reformed
- carry chemical groups between enzyme controlled reaction together
- induced fit hypothesis
- active site is cavity in which the substrate fits
- initially the active site is not correct to fit the substrate
- as the substrate approaches the active site changes shape to become complementary
- after the reaction takes place and the products are gone the active site returns to its original shap
- lock and key hypothesis
- active site already exact complementary shape for substrate, like a lock and key
- factors effecting rate of reaction
- temperature
- as temperature rises kinetic energy increases
- more molecules move which increases rate of reaction
- increases up to optimum
- bonds are broken holding enzyme in correct strcuture
- enzyme eventually denatures
- PH
- changes in PH can break bonds
- this changes the 3D shape of the enzyme
- fewer es complexes form
- enzyme concentration
- rate of reaction proportional to enzyme concentration
- more es complexes formed increases chance of collisions
- substrate concentraion
- rate of reaction increases with increasing substrate concentration up to a point
- the enzyme substrate concentration has to dissacoaite before more substrate can bind
- on a graph it rises to then level off
- temperature
- enzymes are...
- speed up the rate of reaction
- catalysts
- are not chemically altered
- only a small amount needed to alter the rate
- need to be in an aqueous solution as this allows the enzyme and substrate to move around
- intracellular (inside cells)
- extracellular (outside cells)
- metabolism
- catabloic respiration
- substrate broken down e.g respiration
- catalysed by enzymes
- anabolic respiration
- used to build a new molecule
- formation of cellulose for cell walls
- catalysed by enzymes
- catabloic respiration
- end product inhibition
- stops reaction at end as substrate cannot bind to active site
- competitive inhibitors
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