Topic 1a- Enzyme- controlled reactions

Question 1

You are testing the effects of pH on the action of an enzyme. What other variables must you keep constant?

Answer 1

Enzyme concentration, substrate concentration, temperature.

Question 2

How do you work out initial rate of reaction?

Answer 2

1. Draw a tangent to the curve at time = 0.
2. Make the tangent as large as possible.
3. Calculate the gradient of the tangent (change in y/change in x).
4. This equals the initial rate. Alternatively, the initial rate is equal to the negative of the slope of the curve of reactant concentration versus time at t = 0

Question 3

What are the 2 ways of measuring the rate of an enzyme- controlled reaction?

Answer 3

• You can measure how fast the product of the reaction is made.
• You can measure how fast the substrate is broken down.