Purpose: The purpose of this lab is to test for enzyme activity, look at enzyme specificity, and how temperature affects enzyme activity.
Time need to perform this lab: approximately 3 hours
Preparation
FIRST: Read the lab in its entirety TWICE before you begin. You will perform the experiment, write your lab report and include the answers to the additional 4 questions within the text for full credit on this experiment.
Materials:
•3% hydrogen peroxide
•a household blender
•potatoes (3 medium size potatoes, that are peeled and quartered) •tap water
•8 test tubes
•8 transfer pipets
•sugar packets
•salt
•a small saucepan
•a refrigerator with a freezer
•stove
•4 clear plastic cups
•tongs (to remove test tubes from boiling water)
•4 coffee cups
•cheesecloth to filter the potato extract
•a wax pencil or Sharpie marker
•a ruler
•scale or balance
•250 ml graduated cylinder
•oven mitt or tongs
Preparation Step 1: Research (online) the reaction between catalase and hydrogen peroxide and be familiar with the reactants, products, and enzyme. You will include the overall reaction in your lab report for this experiment. We will measure enzyme activity by measuring the height of the bubbles produced.
Questions
1.Given your research, why are we measuring the height of the bubbles produced to indicate how much enzyme activity has occurred? 2.What product are we specifically observing being produced?
The Essay on Potato Enzyme Lab
An enzyme is a protein that speeds up or slows down a specific chemical reaction in an organism. A good rule of thumb is to remember that enzyme names end in “-ase”. This will help in identifying enzymes in further readings. Generally enzymes are catalysts. Hydrogen peroxide is a toxic chemical that is produced in many organisms during metabolism. Organisms must get rid of this toxin to survive. ...
Preparation Step 2:
1.Prepare the potato extract (catalase) using the following technique: •peel 3 medium size potatoes and cut them into quarters
•add the potatoes to the blender with 250 mls of tap water to cover the potatoes and blend on high until the potatoes are pureed (blended to a thick liquid or paste) •place a cheesecloth over a container and use the cheesecloth to obtain the liquid portion (only) of your potato puree. You can squeeze the cheesecloth in the end to obtain the final portions of the liquid from the puree. 1.Make a 1% sucrose solution using the method describe in your osmosis lab. 2.Make a 1% salt solution by measuring 1 gram of salt using your scale or balance, add this to your graduated cylinder and then fill to the 100ml mark. You can then transfer this mixture to a small saucepan, heat and stir until the mixture is dissolved.
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Procedure
Experiment 1: Testing for Enzymatic Activity
For this experiment, you will need:
•4 test tubes
•ruler
•water
•1% sucrose (sugar) solution
•1% salt solution
•3% hydrogen peroxide
•catalase (the liquid portion of your potato extract)
•4 clear plastic cups
•wax pencil
•transfer pipets
Step 1: Add 3mls of the following solutions to a labeled test tube using a fresh transfer pipet with each new solution:
•test tube 1: tap water
•test tube 2: 1% sucrose solution
•test tube 3: 1% salt solution
•test tube 4: 3% hydrogen peroxide
Questions
1.Why is it important to use a fresh transfer pipet for each new solution? Step 2: Add 2 mls of the catalase solution (liquid portion of the potato extract) to each test tube and place into a plastic cup to keep it upright. Pick up each test tube, tap the bottom/ swirl the contents and then using your ruler record in Table 1 the bubble height (if any) that is produced. Remember to include this table (with a strong title) in your lab report.
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Experiment 2- Testing the Effect of Temperature on Enzyme Activity
For this experiment, you will need:
•4 test tubes
•ruler
•3% hydrogen peroxide
•catalase (the liquid portion of your potato extract)
•4 coffee cups
•wax pencil
•transfer pipets
•refrigerator w/ freezer
•stove
•saucepan
•tap water
•oven mitt or tongs
Step 1: Label the test tubes 1, 2, 3 and 4, where test tube 1 represents the sample placed on the counter at room temperature, test tube 2 represents the tube placed in the refrigerator, test tube 3 represents the tube placed in the freezer, and test tube 4 represents the sample exposed to boiling water. You will expose catalase to each of these four conditions.
Questions
4.Before you begin, predict under which treatment you expect to see the most enzyme activity and explain why you think that will happen. Step 2: Place a saucepan with tap water on a burner and bring to a boil.
Step 3: Use the thermometer to identify and record the temperature for room temperature, in your refrigerator, in your freezer, and then research the temperature of boiling water (do not take this temperature) and record them in Table 2.
Step 4: Place the test tubes into separate coffee cups to maintain the upward position. Add 2 mls of the catalase solution to each of the test tubes and then place tubes1, 2, and 3 in the conditions described above. For test tube 4, fill the coffee mug half full of boiling water and then place test tube 4 in this container. Do not place the test tube into the pan of boiling water.
Step 5: Allow the tubes to sit for 5 minutes, then remove the tubes from the conditions mentioned above (note: be careful to use an oven mitt or tongs to remove the test tube exposed to boiling water from the coffee cup).
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Step 6: Then add 3 mls of 3% hydrogen peroxide, swirl all tubes, and measure the bubbles produced by measuring bubble height (if any are produced).
Record this data in Table 2.
Results
Please include your results in two tables that are clearly labeled and have columns for the contents of each test tube, the treatment if applicable (experiment 2) and the height of the bubbles produced (if any).
Conclusions
For this portion, include the results obtained and an interpretation of the results. Also state whether the results were expected or not and, if the results are unexpected, include possible reasons for this and what your next step should be. Remember to also include your answers to the 4 Questions embedded in the experiment above for full credit.
Submission: Create your lab report using word-processing software, such as Microsoft Word and save it to your computer as a .doc, .docx, or .rtf file. To submit the report, choose the link titled, Lab 6: Enzymes, above. Use the “Browse My Computer” button in the Attach File area to attach your document. Be sure to complete your submission by choosing the “Submit” button at the bottom of the screen.
