Enzyme Activity Lab
Investigate catalase activity and discover how temperature, pH, substrate concentration and enzyme concentration influence the rate of an enzyme-controlled reaction.
Enzyme–Substrate Model
Catalase accelerates the decomposition of hydrogen peroxide.
Select the experimental conditions and press Run Experiment.
🎯 Aim
To investigate how temperature, pH, substrate concentration and enzyme concentration affect the activity of catalase.
🧰 Virtual Materials
Catalase source, hydrogen peroxide solution, test tube, thermometer, pH conditions, oxygen-bubble indicator and observation table.
📘 Theory
Enzymes are biological catalysts. They increase the rates of specific biochemical reactions without being consumed in the overall reaction.
2H₂O₂ → 2H₂O + O₂
The oxygen produced can appear as bubbles or foam.
🧬 Factors Affecting Enzyme Activity
Temperature
Low temperature generally slows molecular movement and reaction rate. Excessive heat can alter enzyme structure and reduce activity.
pH
Enzymes have characteristic pH ranges. Strong departures from suitable conditions can alter interactions involved in enzyme structure and active-site function.
Substrate
Increasing substrate concentration can increase reaction rate until enzyme active sites become effectively saturated.
Enzyme
With sufficient substrate, increasing enzyme concentration provides more available active sites and can increase the reaction rate.
🔐 Enzyme–Substrate Interaction
A substrate interacts with a particular region of an enzyme called the active site. The chemical and three-dimensional properties of the active site help determine which substrates can interact effectively with the enzyme.
📋 Observation Table
| Trial | Temperature | pH | Substrate | Enzyme | Relative Rate | O₂ Output | Observation |
|---|---|---|---|---|---|---|---|
| Run an experiment and press Record. | |||||||
⚖️ Fair-Test Investigation
When studying one factor, change only that independent variable while keeping the other experimental conditions as constant as reasonably possible.
📝 Procedure
- Start with 37°C, pH 7, Medium substrate and Medium enzyme.
- Press Run Experiment.
- Observe oxygen bubbles, foam and relative reaction rate.
- Press Record.
- Change temperature while keeping the other factors constant.
- Compare 10°C, 37°C and 70°C.
- Reset temperature and investigate pH.
- Investigate substrate concentration.
- Investigate enzyme concentration.
- Compare all recorded observations.
🧠 Prediction Challenge
🎓 Quick Viva
1. What is an enzyme?
An enzyme is a biological catalyst that increases the rate of a chemical reaction without being consumed in the overall reaction.
2. What is catalase?
Catalase is an enzyme that catalyses the decomposition of hydrogen peroxide into water and oxygen.
3. What is the substrate in this experiment?
Hydrogen peroxide is the substrate for catalase.
4. Why are bubbles produced?
Oxygen gas is produced when catalase catalyses the decomposition of hydrogen peroxide.
5. Why does low temperature slow enzyme activity?
At lower temperatures, molecules generally have less kinetic energy, reducing the frequency of productive enzyme–substrate interactions.
6. What is denaturation?
Denaturation is disruption of a protein’s functional three-dimensional structure. If the active site’s structure is sufficiently altered, enzyme activity can decrease greatly.
7. Why can reaction rate level off at high substrate concentration?
When most available enzyme active sites are occupied frequently, adding additional substrate may produce little further increase in reaction rate unless more enzyme is available.
8. Does every enzyme work best at pH 7?
No. Different enzymes have different pH optima and functional ranges depending on their structure and biological environment.
✅ Result
The simulation demonstrates that enzyme activity depends on experimental conditions. Catalase activity can change with temperature and pH, while increasing substrate or enzyme concentration can increase reaction rate when the other necessary component is available. Extreme conditions can reduce enzyme activity by disrupting the molecular interactions required for normal enzyme structure and function.