The mechanism of enzyme action 2.4.3

Question 1

What is an enzyme substrate complex (ESC)?

Answer 1

Enzyme molecule with substrate molecules in the active site, joined by non-covalent forces (temporarily)

Question 2

What is an enzyme-product complex?

Answer 2

When the bound substrate is converted to product by catalytic groups within the active site - it is joined temporarily by non-covalent forces.

Question 3

Describe the lock and key hypothesis

Answer 3

States that the active site of the enzyme has a shape that is complimentary to that of the substrate.

Question 4

Describe the induced fit hypothesis

Answer 4

Explains that when the substrate molecule fits into the enzymes active site, the active site changes shape slightly (due to changes in the R groups of the amino acids) to mould itself around the substrate molecules.

Question 5

What do enzymes do to a reaction?

Answer 5

They lower the activation energy required for a chemical reaction to occur.
(This cannot be done by increasing temperature in living cells, so enzymes bring the substrate molecules close enough together to react without excessive heat - lowering the activation energy).

Question 6

Why are enzymes catalysts?

Answer 6

Because they lower the activation energy needed to drive a reaction.