what are enzymes?
they are proteins with a tertiary structure, with a specific active site, which can bind to a complimentary substrate
what is the role of enzymes?
molecules which speed up the rate of reaction by acting as catalysts,
what complex do enzymes form?
enzyme-substrate complex
how do enzymes speed up the process of an enzyme
lowering the activation energy required for a chemical reaction
name the two enzyme models
- Lock and Key model
- Induced fit model
outline the lock and key model
- original model
- active site is exactly specific and complimentary to substrate molecule
- substrate fits exactly when they collide forming an enzyme-complex substrate
name the factors which affect enzyme action
- enzyme concentration
- substrate concentration
- temperature
why is enzyme concentration a factor affecting enzyme concentration
- increased enzyme concentration increases active site availability
- allows more enzyme substrate complexes to form
- rate of reaction increases as the substrate becomes the limiting factor
(Linear then platueus graph)
how does substrate concentration act as a factor affecting enzyme action
- more substrate molecules increases rate of reaction
- more collisions occur forming more enzyme-substrate complexes
- rate of reaction eventually slows as enzymes become a limiting factor
(Slowly curves)
how does temperature affect the enzyme action?
- temperature increases so does rate of reaction
- more kinetic energy
- more enzyme substrate complexes
- most effective at optimum temperature
- at high temperatures denaturation occurs, breaking H bonds and changing shape of tertiary structure and therefore active site
- stopping complex formation
(Bell shaped curve)
define enzyme inhibitors
enzyme activity being slowed or prevented by other molecules that are not substrates
name two types of inhibitors
- competitive inhibition
- non-competitive inhibition
outline competitive inhibition
- similar shape to substrate
- compete with substrate
- bind to active site
- prevents enzyme-substrate complexes being formed
- increasing concentration of substrate will reverse the effects of a competitive inhibitor
(higher line on graph than non-competitive)
outline non-competitive inhibitors
- bind away from the active site
- binds to the allosteric site
- causes tertiary shape to changes
- affects the complimentary active site
- no enzyme-substrate complexes can be formed
- increasing concentration of substrate will have no effect
