Enzyme action Flashcards
what are enzymes?
enzymes are tertiary structure proteins which catalyse reactions (biological catalysts )
what is an active site ?
a small part of the enzyme that attaches to a substrate to catalyse a reaction
what are the features of the active site ?
they are specific and unique in shape
why is the active site specific and unique in shape ?
due to the specific folding and bonding in the tertiary structure of the protein
- due to this specific active site, enzymes can only attach to substrates that are complementary in shape
what is meant by the activation energy ?
the minimum amount of energy needed for a reaction to occur
what do enzymes do to the activation energy ?
when enzymes attach to the substrate they can lower the activation energy needed for the reaction to occur by providing an alternative reaction pathway with a lower activation energy
what are the 2 models of enzyme action called ?
- lock and key model
- induced fit theory / model
what does the lock and key model suggest overall ?
the model suggests that the enzyme is like a lock and the substrate is like a key that fits into it due to their complementary shapes
draw the lock and key model
from notes
what does the lock and key model suggest specifically ?
the model suggests that the enzymes active site is a fixed shape and that due to random collisions the substrate can collide and attach to the enzyme, to form enzyme-substrate complexes
what occurs once the enzyme substrate complexes have formed in the lock and key model ?
the charged groups within the active site are thought to distort the substrate and therefore lower the activation energy. the products are then released and the enzymes active site is empty and ready to be reused
draw the induced fit model
notes
what does the induced fit model suggest ?
this model suggests that the enzyme is like a glove and the substrate is like your hand
- the empty glove is not exactly complementary in shape to your hand, but when your hand enters it enables the glove to mold around your hand to become completely complimentary
what is meant by induced fit ?
when the enzymes acrive site is induced or slightly changes shape to mold around the substrate
what happens in the induced fit model when the enzyme-substrate complex occurs ?
due to the enzyme molding around the substrate it puts strain on the bonds and weakens the bonds and therefore lowers the activation energy. the products are then removed and the enzyme active site returns to its original shape
