Lactase Enzyme Introductory Bio II Lab PDF

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Lactase Enzyme Activity with Data Analysis Simulation at https://sites.google.com/site/biologydarkow/lactase-with-variable-sample-sizes Pre-Lab 1. Define the following and explain how each relates to the lactase chemical reaction. ➔ Enzyme Enzyme is a protein that speeds up the rate of a chemical reaction without it being chemically changed at the end of the reaction. ➔ Substrate The substrate is the reactant that binds to the enzyme's active site and is transformed into products. ➔ Active site The active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. ➔ Rate of reaction The reaction rate or rate of reaction is the speed at which a chemical reaction takes place. ➔ Activation Energy The energy required to initiate the reaction is called the activation energy. 2. What is the chemical reaction that lactase catalyzes? Lactase catalyzes the hydrolysis of the bond in lactose, releasing galactose and glucose. 3. Why would having the enzyme lactase as an adult be an evolutionary advantage? This would be an evolutionary advantage because the adult would be able to eat dairy and not get sick from it, resulting in a higher chance of survival. 4. Explain how the structure of an enzyme relates to how well the function catalyzes chemical reactions. The structure of an enzyme is important because it allows for the correct substrate to enter the active site. If the enzyme is inhibited it cannot catalyze reactions because the substrate will not bind. Since enzymes can change shape slightly to fit the substrate (induced fit), they are able to catalyze reactions faster because they fit the substrate very well. 5. Draw three models of how the structure of an enzyme relates to how well the function catalyzes chemical reactions. Model 1 should be a fully functioning enzyme.

Model 2 should be a poorly functioning enzyme.

Model 3 should be a non-functional enzyme.

Simulation Option 1: Temperature 1. Start with the initial glucose at 48 mM and the pH at 7. Do not vary these parameters while testing for temperature, they are environmental controls. The temperature is in degrees Celsius. Be sure to show the instructor your method for calculating the rate of reaction for the first 10 minutes before going on. The units should be mM glucose per minute (mM/min). Vary the temperature by 20o C. Run each experiment 5 times (for reliability in the results.) Record the rate of reaction in the table below. The rate of reaction should be in mM of glucose per minute. 0oC

20oC

40oC

60oC

80oC

Trial 1

0

1.43

0.63

0

0

Trial 2

0

1.51

0.457

0

0

Trial 3

0

1.4

0.36

0

0

Trial 4

0

1.13

0.447

0

0

Trial 5

0

1.58

0.491

0

0

Mean

0

1.41

0.477

0

0

2. On the axes provided, create a  n appropriately labeled graph to illustrate the sample means of the five

temperatures tested.

3. What are the results of the simulation? What is the optimal temperature? The simulation showed that the optimal temperature is around 20 degrees celsius. Once the temperature reaches 60 degrees celsius, the enzyme denatures, and it does not function. 4. Explain why your results of the optimal temperature of the lactase enzyme make sense for the human enzyme? Explain the results in terms of the structure and function of proteins. The optimal temperature makes sense for human enzymes because human body temperature is around 20˚C. At the optimal temperature or the average human body temperature the structure of a protein is not denatured. Also, a protein's function is not inhibited at these temperatures because the temperatures allow them to have an optimal structure in order to perform optimally. 5. Propose an appropriate control treatment for the experiment, and describe how the control treatment would increase the validity of the results. An appropriate control group for the experiment would be to ensure the pH, initial glucose amount, initial enzyme concentration, salinity, and pressure are all constant. This would increase the validity of the results because it would ensure that the only environmental change is the temperature. It also guarantees that nothing else could effect the rate of reaction other than temperature. 6. Predict how the milk digestion is affected in individuals that lack functional copies of the gene encoding lactase. Justify your response. The milk digestion in those individuals would happen much slower because lactase is not present to catalyze the reaction. Since the purpose of enzymes is only to speed up reactions, the milk would still get digested, but it would take a long time because nothing would be present to reduce the activation energy and catalyze the reaction.

Simulation Option 2: pH 1. Start with the initial glucose at 48 mM and the temperature at 25 degrees. Do not vary these parameters while testing for temperature, they are environmental controls. Be sure to show the instructor your method for calculating the rate of reaction for the first 10 minutes before going on. The units should be mM glucose per minute (mM/min). Vary pH by 3. Run each experiment 5 times (for reliability in the results.) Record the rate of reaction in the table below. The rate of reaction should be in mM of glucose per minute. 1

4

7

10

13

Trial 1

0.802

11.2

9.96

5.62

0.01

Trial 2

0.677

8.98

21.9

8.78

0.009

Trial 3

0.513

14

14.1

7.1

0.01

Trial 4

0.632

10.7

27.6

6.26

0.008

Trial 5

0.695

9.73

19.5

6.91

0.008

Mean

0.6638

10.922

18.612

6.934

0.009

 n appropriately labeled graph to illustrate the sample means of the five 2. On the axes provided, create a temperatures tested.

3. What are the results of the simulation? What is the optimal pH? The simulation shows that the optimal pH of the experiment is 7. 4. Explain why your results of the optimal pH of the lactase enzyme make sense for the human enzyme? Explain the results in terms of the structure and function of proteins. This pH makes sense for a human enzyme because humans are mostly composed of water which has a pH of 7. At pH 7, proteins are not denatured and are able to have an optimal structure, so their function is also optimal because they are able to perform their job effectively. 5. Propose an appropriate control treatment for the experiment, and describe how the control treatment would increase the validity of the results. An appropriate control would be to keep the temperature, initial glucose amount, initial enzyme concentration, salinity, and pressure constant. This would increase the results' validity because it would ensure that the pH is the only thing effecting the enzyme's rate of reaction. 6. Predict how the milk digestion is affected in individuals that lack functional copies of the gene encoding lactase. Justify your response. The milk digestion in those individuals would happen much slower because lactase is not present to catalyze the reaction. In this case, enzymes would denature at a certain pH, meaning that the pH can’t be too high or too low, or it affects the function of the enzyme.

Simulation Option 3: Substrate Concentration

1. Start with the temperature at 25 degrees and pH at 7. Do not vary these parameters while testing for temperature, they are environmental controls. The concentration is in mM. Be sure to show the instructor your method for calculating the rate of reaction for the first 10 minutes before going on. The units should be mM glucose per minute (mM/min). Vary substrate by . Run each experiment 5 times (for reliability in the results.) Record the rate of reaction in the table below. The rate of reaction should be in mM of glucose per minute. 20

40

60

80

100

Trial 1

10.9

14.9

23

23.9

21.9

Trial 2

11.8

18.9

21.4

27.5

26.7

Trial 3

13.3

20.7

25.3

26.6

24.9

Trial 4

14.6

20.4

23.6

32

23.8

Trial 5

9.78

24.5

26

19.9

29

Mean

12.076

19.88

23.86

25.98

25.26

2. On the axes provided, create a  n appropriately labeled graph to illustrate the sample means of the five

temperatures tested. 3. What are the results of the simulation? What is the optimal concentration? The simulation shows that the optimal substrate concentration is 80mM. 4. Explain why your results of the optimal concentration of the lactase enzyme make sense for the human enzyme? Explain the results in terms of the structure and function of proteins. Since there is only a certain amount of enzymes in the human body, there is a certain point where all the enzymes are processing substrates and it can no longer reach a higher reaction rate.

5. Propose an appropriate control treatment for the experiment, and describe how the control treatment would increase the validity of the results. An appropriate control group would be testing the rate of reaction where all factors are constant. This ensures that the substrate concentration would be the only thing affecting the rate of reaction rather than potential external factors. 6. Predict how the milk digestion is affected in individuals that lack functional copies of the gene encoding lactase. Justify your response. The milk digestion in those individuals would happen much slower because lactase is not present to catalyze the reaction. In this case, since there is more substrates but the same amount of enzymes, the milk would not be processed any faster than a certain rate, which is its peak....