Which test tubes would be used to determine the optimal pH for lipase activity in an experiment?

• A. Test tubes containing only substrate at neutral pH
• B. Test tubes containing lipase and substrate at different temperatures (e.g., 25°C, 37°C, and 50°C)
• C. Test tubes containing lipase and substrate at different pH values (e.g., pH 4, 7, and 9)
• D. Test tubes containing lipase and substrate with varying substrate concentrations at constant pH

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the goal of the experiment. The objective is to determine the optimal pH for lipase activity, which means identifying the pH at which lipase functions most effectively to catalyze the breakdown of its substrate.
2. Step 2: Recall the concept of enzyme activity and pH. Enzymes like lipase have an optimal pH range where their structure and active site are most conducive to catalysis. Outside this range, the enzyme may denature or lose efficiency.
3. Step 3: Analyze the options provided. To determine the optimal pH, you need to test lipase activity across a range of pH values. This requires test tubes containing both lipase and substrate at different pH levels (e.g., pH 4, 7, and 9). Other options, such as varying temperature or substrate concentration, do not directly address pH dependence.
4. Step 4: Design the experiment. Prepare test tubes with lipase and substrate, ensuring the pH of each tube is adjusted to a specific value within the range you want to test. For example, you might use buffers to maintain pH levels at 4, 7, and 9.
5. Step 5: Measure lipase activity in each test tube. This can be done by monitoring the rate of substrate breakdown (e.g., production of fatty acids or glycerol) using appropriate assays. Compare the activity across different pH values to identify the optimal pH for lipase.