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Pre-Lab Questions

1. How could you test to check out if one enzyme was totally saturated during an experiment?

2. Perform three conditions that would change the task of an enzyme. Be specific with your explanation.

You are watching: 1. what reaction is being catalyzed in this experiment?

3. Take a look approximately your house and identify household assets that work-related by way of an enzyme. Name the products, and indicate how you recognize they job-related with one enzyme.

Experiment 1: enzyme in Food

This experiment tests for the visibility of amylase in food by using Iodine-Potassium Iodide, IKI. IKI is a shade indicator used to detect starch. This indicator turns dark violet or black color in shade when in the existence of starch. Therefore, if the IKI systems turns come a dark violet or black shade during the experiment, one deserve to determine that amylase is not existing (because existence of amylase would breakdown the starch molecules, and also the IKI would certainly not readjust color).


(1) 2 oz. Bottle (Empty) (1) 100 mL graduated Cylinder 30 mL Iodine-Potassium Iodide, IKI permanent Marker ruler 2 Spray covering 30 mL strength (liquid) *Cutting Board


*2 Food assets (e.g., ginger root, apple, potato, etc.) *Kitchen Knife *Paper bath towel *Saliva Sample *Tap Water

*You must Provide


1. Eliminate the cap from the starch solution. Affix the spray lid to the starch solution.

2. Rinse out the empty 2 ounce bottle through tap water. Use the 100 mL i graduated cylinder come measure and pour 30 mL the IKI into the empty 2 ounce bottle. Affix the remaining spray lid come the bottle.

3. Collection up a positive regulate for this experiment by spraying a paper towel v the strength solution. Enable the strength to dried for roughly one hour (this time interval may vary by location).

4. In the median time, set up a an unfavorable control because that this experiment. Usage your expertise of the scientific an approach and experimental controls to establish this ingredient (hint: what should take place when IKI equipment contacts something that does not contain starch?) recognize your an adverse control in Table 1.

Note: Be certain to an are the confident and negative controls apart from each various other to stop cross-contamination.

5. As soon as the starch solution has actually dried, test your positive and an unfavorable controls. This step creates a baseline color scale because that you to evaluate the strength concentration of the food commodities you will test in steps 7 – 11. Record your outcomes in Table 1.

6. Pick two food items from your kitchen room or refrigerator.

7. Acquire a kitchen knife and also a cutting board. Carefully cut your selected food item to develop a fresh surface.

Figure 3: Sample set-up.

8. Gently obstacle the fresh/exposed area that the food items on the dry, starch-sprayed document towel earlier and forth 10 – 15 times. Label wherein each specimen was rubbed ~ above the file towel with a long-term marker (Figure 3).

9. Wash her hands with soap and water.

10. Take her finger and place the on her tongue to transfer some saliva to your finger. Then, rub your moistened finger saliva into the file towel. Repeat this action until you room able to adequately moisten the document towel. Note: you should constantly wash your hands before touching your tongue! Alternatively, if you do not wish to put your hand in her mouth, you might also carry out a saliva sample through spitting in a different bowl and also rubbing the record towel in the saliva. Be certain not come spit on the document towel directly as you may unintentionally cross-contaminate your samples.

11. Wait 5 minutes.

12. Hold the IKI spray bottle 25 – 30 cm away indigenous the file towel, and mist with the IKI solution.

13. The reaction will certainly be complete after about 60 seconds. Observe where color develops, and consider what these results indicate. Document your outcomes in Table 1.

Table 1: substance vs. Starch Presence
SubstanceResulting ColorPresence that Starch?
Positive Control: StarchDark PurpleYes
Negative manage : CelluloseBrownish red color No
Food Product: AppleDark Purple yes
Food Product: PotatoDark Purple yes
Saliva: AmylaseBrownish red color No

Post negative Control -Lab Questions

1. What were your controls because that this experiment? What walk they demonstrate? Why to be saliva contained in this experiment?

2. What is the function of amylase? What walk amylase execute to starch?

3. I beg your pardon of the foodstuffs that you tested had amylase? Which go not? What experimental evidence supports your claim?

4. Saliva does no contain amylase till babies are two month old. How could this affect an infant’s cradle requirements?

5. There is an additional digestive enzyme (other than salivary amylase) the is secreted by the salivary glands. Research study to identify what this enzyme is called. What substrate does it act on? where in the body does it become activated, and why?

6. Digestive enzyme in the gut encompass proteases, i beg your pardon digest proteins. Why nothing these enzymes digest the stomach and little intestine, which are partly composed the protein?

Experiment 2: result of Temperature on Enzyme Activity

Yeast cell contain catalase, an enzyme which helps transform hydrogen peroxide come water

Figure 4: Catalase catalyzes the decomposition of hydrogen peroxide to water and also oxygen.

and oxygen. This enzyme is very far-reaching as hydrogen peroxide have the right to be toxicity to cells if enabled to accumulate. The impact of catalase can be seen as soon as yeast is linked with hydrogen peroxide (Catalase: 2 H2O2 → 2 H2O + O2).

In this lab friend will examine the results of temperature ~ above enzyme (catalase) activity based ~ above the amount of oxygen produced. Note, be certain to remain observant for effervescence when assessing your results.


(2) 250 mL Beakers 3 Balloons 30 mL 3% Hydrogen Peroxide, H2O2 measure Spoon long-term Marker leader 20 cm String


3 check Tubes (Glass) Test tube Rack Thermometer Yeast Packet *Hot Water bathtub *Stopwatch *You have to Provide


1. Usage a irreversible marker to label test pipe 1, 2, and also 3. Place them in the test pipe rack.

2. Fill each tube through 10 mL hydrogen peroxide. Then, keep one of the check tubes in the test pipe rack, however transfer the two added test tubes to two different 250 mL beakers.

3. Find one that the balloons, and also the piece of string. Wrap the string about the uninflated balloon and measure the size of the string v the ruler. Document the measure in Table 2.

4. Create a warm water bath by performing the complying with steps:

a. Determine if you will usage a stovetop or microwave to warm the water. Use the 100 mL i graduated cylinder to measure and pour about 200 mL of water into a tiny pot or microwave-safe key (you will need to measure this volume in two separate allocations).

b. If making use of a stovetop, obtain a tiny pot and proceed to action 4c. If using a microwave, attain a microwave-safe bowl and proceed to step 4e.

c. If using a stove, ar a tiny pot ~ above the stove and also turn the cooktop on to a medium warmth setting.

d. Carefully monitor the water in the pot till it concerns a soft boil (approximately 100 °C). Use the thermometer detailed in her lab kit come verify the water temperature. Revolve the cooktop off once the water begins to boil. Automatically proceed to action 5. CAUTION: Be certain to turn the oven off after producing the warm water bath. Screen the heater water at every times, and never manage a hot pan without proper pot holders.

e. If making use of a microwave, place the microwave-safe key in the microwave and also heat the water in 30 second increments till the temperature of the water is around 100 °C. Usage the thermometer listed in her lab kit to verify the water temperature. Wait around one minute before proceeding to step 5.

5. Ar Tube 1 in the refrigerator. Leave tube 2 at room temperature, and also place tube 3 in the warm water bath.

Important Note: The water have to be at approximately 85 °C once you place Tube 3 in it. Verify the temperature with the thermometer come ensure the water is not too hot! temperatures which exceed approximately 85 °C may denature the hydrogen peroxide.

6. Record the temperature of each condition in Table 2. Be sure to provide the thermometer with sufficient time in in between each environment to prevent obscuring the temperature readings.

7. Permit the tubes sit because that 15 minutes.

8. During the 15 minutes prepare the balloons through yeast by adding ¼ tsp. That yeast every balloon. Make sure all the yeast gets resolved to the pear of the balloon and not recorded in the neck. Be sure not spill yeast while taking care of the balloons.

9. Closely stretch the neck the the balloon to aid ensure that does no rip as soon as stretched end the opened of the test tube.

10. Connect the neck the a balloon you prepared in step 8 come the height of tube 2 (the room temperature test tube) making sure to no let the yeast spill into the test tube yet. As soon as the balloon is securely attached to the test pipe lift the balloon and allow the yeast to enter the check tube. Madness the pear of the balloon to ensure every the yeast drops into the tube.

11. As quickly and carefully as possible remove the tube 1 (cold) indigenous the refrigerator and also repeat actions 9 – 10 through Tube 1 making use of a balloon you prepared in step 8.

12. Together quickly and carefully as feasible remove pipe 3 (hot) from the hot water bath and also repeat procedures 9 – 10 through Tube 3 using a balloon you ready in step 8.

13. Swirl each tube to mix, and also wait 30 seconds.

14. Wrap the string approximately the center of every balloon to measure the circumference. Measure the size of string through a ruler. Record your dimensions in Table 2.

Table 2: Balloon circumference vs. Temperature
TubeTemperature (°C)Balloon one (Uninflated; cm)Balloon circumference (Final; cm)
1 – (Cold)
2 – (RT)
3 – (Hot)

Post-Lab Questions

1. What reaction is being catalyzed in this experiment?

2. What is the enzyme in this experiment? What is the substrate?

3. What is the independent change in this experiment? What is the dependence variable?

4. Just how does the temperature affect enzyme function? Use evidence from her data to assistance your answer.

5. Draw a graph that balloon diameter vs. Temperature. What is the correlation?

6. Is over there a an unfavorable control in this experiment? If yes, determine the control. If no, suggest just how you could revise the experiment to include a an adverse control.

See more: An Open Fracture Is Most Accurately Defined As A Fracture In Which:

7. In general, how would an increase in substrate alter enzyme activity? attract a graph to show this relationship.

8. Design an experiment to determine the optimal temperature for enzyme function, complete with controls. Whereby would you discover the enzymes for this experiment? What substrate would certainly you use?