Assignment: The Effect of low pH on Enzyme Activity

Design an experiment in which you will test the effect of an acidic fluid on enzymatic activity. Recall: enzymes are proteins! To complete this project, it may be useful for you to first review the Scientific Method Tutorial, information about pH and enzymes in the text book and course modules, Lab 1 (Introduction to Science) and Lab 4 (Enzymes). As you review Lab 4, you will be reminded that there are several factors that impact enzymatic activity: pH, temperature, and amount of reagent. It is OK to use the same enzyme/substrate/method as you did in lab 4 (but modify the treatment), or you can search on-line to find a different enzyme/substrate/method for measuring enzyme activity for your project (include all references).

As you design your experiment for this project, please remember that you are trying to examine how an acidic fluid will modify the outcome of an enzymatic reaction. To successfully complete this project, you will need to identify the question(s) being asked in your experiment and the hypothesis that you are testing. In your experimental design, you must clearly explain what you are doing. That means that you will need to identify the enzyme, the substrate, the acidic fluid used as treatment, the control treatment and the method of measuring enzyme activity, as well as explain your experimental protocol. You must also thoroughly explain how the acidic fluid impacted enzyme activity based on the results from your own experiment as well as knowledge of enzymes and pH from the text book, modules, lab manual and potentially additional information sources.

Hint: Keep in mind that the acid will change the environmental conditions of the experiment (for example, a low pH value could change the shape of the active site on the enzyme protein), without directly participating in the reaction.

Lab Materials

You may need all or some of the following, depending on your experimental design:

Materials from your lab kit:

• pH paper
• hydrogen peroxide solution (you can purchase this at a pharmacy if you have used up the bottle that came with the lab kit)
• plastic beakers or cups
• vinegar
• yeast (can be purchased at grocery store if more is needed)
• balloons
• plastic bottle
• marker for labeling of beakers
• Cell phone/digital camera – pictures required

You may choose to use additional materials (different acidic fluids and/or different organisms and/or different substrate if you chose an enzyme other than catalase).

Outline:

Include the following in your outline:

• Name of enzyme you will use
• Name of organism (if applicable)
• The substrate and products in the chemical reaction
• Method for measuring enzyme activity
• Treatment: acidic fluid(s), pH, length of exposure, how you will treat your samples
• The control(s) in the experiment
• Hypothesis
• How you will present your data (table and/or type of graph)
• Anything else you would like to get feedback on before you start your experiment

Write a lab report that includes the following:

1. Title page: descriptive title, your name, course name, semester

2. Introduction: general background information about enzymes and specific information about your chosen enzyme, the question(s) that you are asking and a clear hypothesis for your experiment.

3. Design an experiment. Provide a detailed description of the materials and methods used to conduct the experiment. Identify control and experimental samples, as well as independent and dependent variables. Also include the methods used for data collection and analysis.

4. Conduct the experiment and record your results. Take picture of results. What did you observe? Present your data in table and/or graph format. Remember to label everything and include the unit of measure with all numbers.

5. Use your knowledge of enzymes and pH to interpret and discuss your results. It may be necessary for you to refer to the text book and course modules, lab manual and/or use additional information resources. What effect does the acidic treatment have on enzyme activity? Did you get the expected results? Explain.

6. State a specific and accurate conclusion. Is your hypothesis supported by the results? Looking back, how could you have improved your experiment?

7. Include a list of references to all information sources used in APA format.