Required Practical 1

Question 1

Examples of variables that can affect rate of an enzyme-controlled reaction

Answer 1

• enzyme concentration
• substrate concentration
• temperature
• pH
• inhibitor concentration

Question 2

How can temperature be controlled?

Answer 2

• use a thermostatically controlled hot water bath
• monitor using a thermometer at regular intervals and add hot/cold water if temp fluctuates

Question 3

How can pH be controlled?

Answer 3

• use buffer solution
• monitor using pH meter at regular intervals

Question 4

Why are enzyme and substrate solutions left in the water bath for 10 mins before mixing?

Answer 4

• so solutions equilibrate / reach temperature of the water bath

Question 5

Describe a suitable control experiment

Answer 5

• use denatured enzymes (eg. By boiling)
• keep everything else the same

Question 6

How can rate of an enzyme-controlled reaction be measured?

Answer 6

• measure time taken for reaction to reach set point
• rate = 1 / time
• measure concentration / volume / mass of substrate at regular intervals
• plot graph with time on x axis and the DV on the y axis
• draw tangent at T = 0