Factors Affecting Enzyme Activity

Question 1

What happens to enzyme activity when temperature is increase up to the optimum temperature?

Answer 1

The rate of reaction increases as temperature increases. More heat means more kinetic energy, so molecules move faster - enzymes are more likely to collide with substrate molecules. Energy of the collisions also increases so each collision is more likely to result in reaction

Question 2

What happens to enzyme activity when temperature is increased past the optimum temperature?

Answer 2

The rise in temp makes the enzyme molecules vibrate more - if temp gets too high the vibration breaks the bonds that hold the enzyme in shape. The active site changes shape, no E-S complexes form and the enzyme is denatured

Question 3

How does pH affect enzyme activity?

Answer 3

All enzymes have an opitmum ph. Above and below this the H+ and OH- ions break the ionic and hydrogen bonds that hold the enzymes tertiary structure in place. The active site changes shape, no E-S complexes form and the enzyme is denatured

Question 4

How does enzyme concentration affect enzyme activity?

Answer 4

More enzymes makes it more likely a substrate molecule will collide with one and form an E-S complex - increases rate of reaction. If substrate is limited there comes a point where there is enough enzyme to deal with the substrate, adding more enzyme has no further effect

Question 5

How does substrate concentration affect enzyme activity?

Answer 5

Higher the substrate conc the faster the rate of reaction - more substrate means more collisions with enzyme molecules. This is true up to the saturation point - all the enzyme active sites are full and adding more makes no difference. Substrate conc decreases over time, so rate of reaction will declares over time as well - this makes the initial rate of reaction the highest

Question 6

What are the two type of enzyme inhibitors?

Answer 6

1. Competitive inhibitors
2. Non-competitive inhibitors

Question 7

Explain competitive inhibition

Answer 7

They have a similar shape to the substrate molecules so they compete with the substrate to bind to the active site, but no reaction happens. They block the active site so no substate can fit in, no E-S complexes form

Question 8

Explain non-competitive inhibition

Answer 8

Non-competitive inhibitor molecules bind to the enzyme away from its active site. This causes the active site to change shape so substrate can’t bind to it, so no E-S complexes can form

Question 9

How do competitive inhibitors molecules affect rate of reaction?

Answer 9

If there’s a high conc of inhibitor, it’ll take up nearly all the active sites so hardly any sister will bind with the enzyme. If there’s a high conc of substrate there’s more chance the substrate will bind to an enzyme than inhibitor. Increasing the conc of substrate will increase rate of reactions