Enzymes Flashcards
How does an enzyme work
Biological catalysts, they make reactions happen faster by reducing the activation energy needed to convert substrates into products
How does an enzyme substrate complex occur
The active site is complementary shape to the substrate
Explain why enzymes are specific
- the active site of an enzyme has a unique shape, only complementary to its own substrate
- active site created by r groups of amino acids brought together when the polypeptide folds into its secondary and tertiary structure
- each polypeptide folds into specific shape due to primary structure
- other molecules don’t have the correct shape to fit into the active site
What happens to the bonds in a substrate when it is bound to an enzyme
The enzyme puts strain on the bond lowering activation energy
Description of lock and key theory
Substrate fits perfectly into active site
The shape of the substrate and enzymes active site are complimentary
Description of induced fit theory
As the substrate binds it forces the active site amino acids into the correct positions to catalyse reaction
The substrate binds to active site of enzyme then the active site changes shape to accommodate the substrate
Effect of temperature on enzyme action
As temp increases to optimum temp the molecules gain more kinetic energy therefore more successful collisions and more ESC can form so more products made
At optimum temp enzymes work at maximum rate
Above optimum temperature hydrogen bonds break affecting tertiary structure= denatures enzyme so no ESC can form, no products
Effect of pH on enzyme action
Enzymes only active in a narrow range of pH
In conditions to acidic or alkaline. Tertiary structure bonds break (hydrogen and ionic), enzyme denatures, no ESC form
At optimum pH ESC forms at maximum rate
Effect of changing substrate concentration
As substrate conc increases the rate of reaction increases initially and then reaches maximum level as all active sites are being used up so more substrates has no effect
Effect of changing enzyme concentration
Increase rate of reaction initially as there are more active sites so more ESC can form
Reaction stops when all substrates are bound to an active site so more enzymes have no effect
What does a competitive inhibitor do
They have a similar shape to substrate so they bind to active site preventing ESC to form
Effect is reversible adding more substrates out competes the inhibitor
What do non competitive inhibitors do
Bind to the enzymes allosteric site and causes the shape of the (tertiary structure) enzyme to change which changes the shape of the active site so enzyme no longer functions no ESC form
This is irreversible adding more substrate does not prevent inhibition
