Name: ________________________________________

Enzyme Lab - Virtual


Overview: In this investigation, you will determine the effects of substrate concentration and pH on the rate of an enzyme-catalzyed reation.

Background:   screenshot

Amylase is an enzyme that catalyses the hydrolysis of starch into sugars. It is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of starch, like bread, may acquire a slightly sweet taste as they are chewed because amylase degrades that starch into sugar.

In the reaction shown, the enzyme is the amylase and the substrate is starch. The program measures theamount of produce produced after the reaction has progressed for 1 minute, allowing you to compare rates of reaction by looking at the amount of end product.

Procecure: The simulation allows you to change two variables: pH level and the amount of available substrate. Data from the simulation can be viewed by clicking on the computer monitor.

*The simulation allows you to input data and print, but due to technical issues with browsers and networked computers, it is preferable to copy the data onto this page.

Data: Collect data for each of the variables and complete the table below. The data collected is "number of molecules of product formed per minute."

Amount of Substrate pH 3 pH 5 pH 7 pH 9 pH 11


1. Use a graphing program like Exel or "Google sheets" to graph the data showing 5 separate lines for each pH level. Attach this graph to this worksheet when you turn it in. To get started, you will be copying the data on the table above to your spread sheet.

Identify the dependent and independent variables (hint: there are two independent variables you investigated, but only one dependent variable.)




2. Describe the relationship between substrate and the product. What happens when you increase the amount of substrate? Predict what would happen if you used 20.g of substrate and explain your reasoning behind the prediction.






3. Explain why the maximum initial reaction rate cannot be reached at low substrate concentrations.



4. What is the optimum pH level for this enzyme? How do you know? Make a prediction about what you think the reaction rate would look like a pH = 2.



5. Enzymes function most efficiently at the temperature of a typical cell, which is 37 degrees Celsius. Increases or decreases in temperature can significantly lower the reaction rate. What does this suggest about the importance of temperature-regulating mechanisms in organisms? Explain.