Topic 1a- Factors Affecting Enzyme Activity

Question 1

Explain the effect of increasing substrate concentration on the rate of an enzyme-catalysed reaction.

Answer 1

As the substrate concentration increases so does the rate of enzyme activity. An optimum rate is reached at the enzyme’s optimum substrate concentration.

Question 2

Inhibitors prevent enzymes from working properly. They can be competitive or non-competitive.
a) Explain how a competitive inhibitor works.
b) Explain how a non-competitive inhibitor works.

Answer 2

a) Competitive inhibitor molecules have a similar shape to the substrate molecules. They compete with the substrate molecules to bind to the active site of an enzyme. When a inhibitor molecule is bound to the active site it stops the substrate molecule from binding.
b) Non- competitive inhibitor molecules bind to enzymes away from their active site. This causes the active site to change shape so the substrate molecule can no longer fit.