ENZYMES: mode of action

Question 1

major steps?

Answer 1

enzyme and substrate bind, forming ES complex

Products are released.

Question 2

how does the enzyme and substrate binding lower activation energy, and reduce rate of reaction?

Answer 2

positions/bends substrate molecules in a way that enables the breaking of existing bonds and the formation of new ones more readily. lowers the activation energy of the reaction, by providing an alternate reaction pathway  the energy of collisions is more likely to be greater than or equal to the new/catalysed activation energy  higher proportion of successful reactions  increased reaction rate.

Question 3

describe lock and key model

Answer 3

assumes active site has fixed shape
active site = lock, substrate = key. shapes must be exactly complementary in order for the key (substrate) to fit into the lock (active site) and thus for the reaction to be catalysed.

Question 4

describe the induced fit model

Answer 4

assumes active site has defined shape, but some flexibility.
When the substrate and active site bind, the active site changes its shape to fit tightly around the substrate. The reaction is catalysed