enzymes Flashcards
what structure proteins are enzymes
- tertiary structure proteins
why can enzymes only attach to substrates that are complimentary in shape?
- the active site is specific and unique in shape
- due to the specific folded and bonding in the tertiary structure of the protein
how/why do enzymes catalyse reactions?
- when enzymes attach to the substrate they lower the activation energy needed for the reaction to occur
what are the two models to explain how enzymes catalyse reactions?
- lock and key model
- induced fit model
explain the lock and key model?
- enzyme 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
explain induced fit model
- active site changes shape to mould around substrate
- this forms enzyme substrate complex and lowers the activation energy
list the factors that affect the rate of enzyme controlled reactions
hint: 5 factors
- temperature
- pH
- substrate concetration
- enzyme concentration
- inhibitors
explain how/why temperature affects enzyme action?
- if temp is too low, not enouhg kinetic energy for successful collisions between enzyme and substrate
- if temp is too high, enzymes denature, active site changes shape and ES complexes cannot form
increased temperature increase kinetic energy leading to more successful
why does denaturation happen?
hint: bonds
- due to breaking of hydrogen and ionic bonds in tertiary structure
how does PH affect enzyme activity?
- too high or low ph interferes with charges in amino acids in active site
- this can break the bonds holding tertiary structure in shape
- can therefore change active site shape
- therefore enzyme denatures and fewer enzyme substrate complexes can form
how does substrate and enzyme concentration affect enzyme activity
- if there is insufficient substrate, the reaction will be slower
- because there is fewer collisions between the enzyme and substrate
if there is insufficient enzymes, active sites become saturated with substrate and unable to work any faster
what are non competitive inhibitors
- bind to allosteric site
- cause active site to change shape
- substrate can no longer bind
- doesnt matter how much substrate is added
what are competitive inhibitors
- same shape as substrate, can bind to active site
- prevent substrate from binding
- if you add more substrate this will out compete the inhibitor
