Lab Assignment
Applied Lab Project
Addresses course outcomes 1-4:
• recognize and explain how the scientific method is used to solve problems
• make observations and discriminate between scientific and pseudoscientific explanations
• weigh evidence and make decisions based on strengths and limitations of scientific knowledge and the scientific method
• use knowledge of biological principles, the scientific method, and appropriate technologies to ask relevant questions, develop hypotheses, design and conduct experiments, interpret results, and draw conclusions
This is the culminating lab assessment in BIOL 102. It is designed to assess your ability to apply the principles of the scientific method.
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(s) of your 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 OLI 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
Name of the Enzyme being used
• Enzyme Amylase
o Amylase is an enzyme found in the digestive tract if human beings as well as other animal.
The Substrate and Products in the Chemical Reaction
• Two Types of Amylase Enzymes
o Salivary Amylase
- Produced in the mouth by the salivary glands.
- Salivary amylase is responsible for starting up the digestion of food in the mouth. It breaks down starch into maltose which is a simple type of carbohydrate.
o Pancreatic Amylase
- Pancreatic amylase completes the digestion of carbohydrates into glucose which is easily absorbable into the blood vessels.
Method for Measuring the Enzyme Activity
• The rate of enzyme activity is measured by the rate at which the product is formed. In the case of enzyme amylase, the rate at which starch is broken down is calculated using time.
• The time taken is recorded at intervals of ten seconds, and then the rate is calculated.
• After that, a graph of rate of reaction is plotted against PH. The rate is calculated by the formulae rate= 1/time
Treatment
• The requirements include 2 test tubes, amylase solution, buffer solution, starch solution, iodine, white tile, stopwatch and test tube rack.
• The iodine solution drops are placed on the white tile in rows. The test tubes are labeled according to the PH to be tested.
o The three solutions are placed in the test tube in the order
- Two cubic centimeter of amylase solution, one cubic centimeter of buffer solution and two cubic centimeter of starch.
- Stir the mixture using a plastic pipette.
- After every ten minutes, removes drops of the solution and place it on the iodine on the tiles until when the color remains orange.
- When the color turns, it means that all the starch has been broken done and the reaction is complete.
- The buffer solution is utilized to prevent the change of PH immediately when the reaction starts
The Controls in the Experiment
• Enzyme Amylase works best at in slightly alkaline conditions.
• The higher the PH, the conversion of the starch to other forms of carbohydrates is lower and thus the presence of starch when tested with iodine solution.
• On the other hand, as the PH is increased, the rate of conversion becomes higher, and more of the starch is converted faster and the absence of the starch as indicated by the brown color of the iodine at the end of the experiment.
Hypothesis
• The hypothesis for the experiment is that there are certain PH values where the rate of reaction or the enzyme activity is highest. The point where the rate of reaction recorded is highest, it is called the optimum temperature.
• It is the temperature at which the enzymes work at its best. The lower the PH value, the lower the rate of reaction and therefore, low conversion of the starch to less complex types of carbohydrates.
Data Table
• The data table will show the results of the experiment followed by verbiage explaining how I determined my results.