Investigation of the effect of temperature on enzyme activity (LC 2026) (Leaving Cert Biology): Revision Notes

Investigation of the effect of temperature on enzyme activity

Background:

Enzymes are affected by temperature. Plant enzymes work best at 30°C, known as their optimum temperature. At other temperatures, the enzyme's activity decreases because temperature changes can alter its shape, leading to denaturation.

Materials needed:

• Hydrogen Peroxide (substrate)
• Celery (contains enzyme catalase)
• pH buffer 9/10 (keeps pH constant)
• Temperature-controlled water bath (varying temperatures: 0°C, 20°C, 30°C, 60°C)
• Washing up liquid
• Graduated cylinders
• Plastic droppers

Method:

1. Place celery, washing-up liquid, and pH buffer in a graduated cylinder.
2. In another graduated cylinder, add 5 cm³ of hydrogen peroxide.
3. Place both graduated cylinders in a thermostatically controlled water bath set at 0°C for 2 minutes to allow all reagents to reach the exact temperature.
4. After 2 minutes, add the hydrogen peroxide to the graduated cylinder containing the other reagents.
5. Record the volume of foam produced after 2 minutes. The foam volume measures enzyme activity by indicating the amount of oxygen produced.
6. Repeat the experiment at 20°C, 30°C, and 60°C.
7. Record the results and plot a graph with temperature on the x-axis (horizontal) and volume of foam (cm³) on the y-axis (vertical).

Results:

Temperature	0°C	20°C	30°C	60°C
Volume of foam cm³/ 2 minutes	0 cm³	5 cm³	15 cm³	5 cm³

Graph of Results: