3.1

Question 1

How do enzymes speed up reactions? (2)

Answer 1

By (1) providing an alternative pathway for reactants to react, (2) lowering the activation energy

Question 2

Explain the lock & key model (4)

Answer 2

(1) substrate = key
(2) enzyme = lock
(3) substrate = complementary to enzyme
(4) substrate = binds to enzyme’s active site

Question 3

How do enzymes get their specific 3D shape? (1)

Answer 3

(1) from their specific sequence of amino acids

Question 4

What happens when the enzyme-substrate complex forms? (2)

Answer 4

(1) temporary bonds…
(2) …form between the substrate & the enzyme’s active site

Question 5

Explain the induced fit model (5)

Answer 5

(1) enzyme = flexible
(2) so enzyme = changes its shape to fit the profile of the substrate
(3) enzyme = puts a STRAIN on the substrate molecule
(4) which DISTORTS a particular bond, …
(5) …which lowers the activation energy