C1.1 - factors affecting enzyme activity (2j)

Question 1

what is collision theory in reference to enzyme activity?

Answer 1

collision theory is the consideration of how factors affect the frequency and success of collisions between two reactants
- enzyme function depends on collisions between substrate and active sites
- the more frequent the collisions, the faster the rate of the reaction
- if molecules collide with more energy, they are more likely to have enough energy to supply the activation energy and allow the reaction to proceed

Question 2

what is denaturation?

Answer 2

denaturation is a permanent change in the conformation of the enzyme active site
- this means the active site of the enzyme cannot bind substrate molecules, so it cannot catalyse the reaction

Question 3

what are the causes of denaturation?

Answer 3

denaturation is caused by extreme pH and by high temperatures

Question 4

what is the effect of temperature on the rate of enzyme activity?

Answer 4

• enzyme activity increases with temperature due to faster molecular motion and more kinetic energy, leading to more collisions
• enzyme reaches highest activity at optimum temperature
• at temperatures above optimum, rate falls as increased vibrations break bonds within the enzyme, so the active site changes

Question 5

what is the effect of pH on the rate of enzyme activity?

Answer 5

• at pH levels below the optimum, ionisation of the amino acid interferes with the ionic bonding and changes the shape of the active site
• enzyme reaches highest activity at optimum pH
• at pH levels above the optimum, ionisation of the amino acid interferes with the ionic bonding and changes the shape of the active site

Question 6

what is the effect of substrate concentration on the rate of enzyme activity?

Answer 6

• enzyme activity increases with substrate concentration due to a greater chance of collisions occurring
• enzyme activity plateaus as enzyme active sites are saturated