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AP Investigation Lab #13 Enzyme Activity

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In the first part of the enzyme lab, we mixed a substrate and an indicator with an enzyme. There was also a neutral buffer in each of the chemical mixtures. The neutral buffer regulated the pH to around 7. We got a color palette and once we mixed each together, we observed and saw a change in the color of the substance. The darker and more brown the substance got, the more oxygen produced by the reaction. Our results showed that amount of oxygen produced increased about 10% a minute until it sort of equilibrated at 4 minutes and didn’t change to the fifth minute mark.

If we were to change anything we did in the experiment, we would make our comparisons to the chart more precise. Overall we thought it was successful.

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In part two of the enzyme lab, we have 12 different test tubes, six of each (#1, 2, 4, 9, 11, and 12) being a substrate with guiacol product indicator, and a neutral buffer. The guiacol is a naturally organic compound and is actually a phosphate.

The other six test tubes (#3, 5, 6, 7, 8, and 10) had the enzyme turnip peroxidase and different pH solutions for each of the six test tubes. The different pH levels were 3, 5, 6, 7, 8, and 10. The lower the pH, the more acidic the liquid is. The higher the pH, the more basic with alkaline. We mixed the six test tubes with the first tube of chemicals with their corresponding tube and pH as labeled in the instructions. We measured the rate of oxygen produced in each using the color palette like we did in part one of this lab. We found that the more neutral (closer to pH 7) the higher the reaction rate.

When the pH level was very acidic or basic, the rate of reaction was lower. In terms of comparison to color, the more neutral the pH, the darker the solution was. The solution was lighter when the rate was lower. This happened because of the enzyme’s tolerance to outside factors. In this experiment, it was pH, but other factors could be temperature and the amount of inhibitors interrupting the reaction. If we could change anything we did in this experiment we would test all pH levels (1-14), line them up in order, then compare them to see if our data was actually correct. We felt this experiment was accurate. Part 3

In part three we were required to design our own experiment. We chose to control the temperature of the enzyme. We thought that if the temperature of the enzyme was increased to 100 degrees Fahrenheit, then the reaction rate would be slowed, if not completely stopped, because of its functional range. When enzymes are at a higher temperature, they are said to be less reactant with substrates. Put neutral buffer, 0.1% H2O2 substrate, and a product indicator. In the other test tube, we put our enzyme, turnip peroxidase, and the neutral buffer and heated it up on a hot plate. This was supposed to decrease the productivity of the enzyme. We mixed the two solutions together and observed them on a minute to minute basis. We were correct in our hypothesis, because the reaction rate was 25% slower. If we could change anything in this experiment that might have gone wrong, we would have had a more accurate temperature reading of our enzyme. It was successful in proving temperature effects enzymes.

Question & Hypothesis
Part 1
Would oxygen be produced if we combined a substrate, enzyme, and a neutral buffer? If all substrate and enzymes create a reaction, then there would be oxygen produced because all reactions have a product created.

Part 2
Do different pH levels affect the percent of oxygen produced in the reaction? If we had to specifically use a neutral buffer with a pH of 7 in part 1, then it would affect the percent of oxygen produced because the different pH levels have a different stabilizing effect.

Part 3
What will happen if we change the temperature of the enzymes to 100° Fahrenheit? If the temperature of the enzyme is increased to 100° Fahrenheit, then the reaction rate will be slowed, if not completely stopped because of its functional range.

Methods and Procedures
Part 1
1. We measured 2.5 mL of 0.1% H2O2 {the substrate), 2.5 mL of guaiacol (the product indicator), and 10 mL of neutral buffer (pH 7) with a syringe and disposed it into test tube SPNB. 2. We inverted twice to mix the SPBN test tube

3. We measured 2.5 mL of turnip peroxidase (the enzyme) and 10 mL of neutral buffer (pH 7) with a syringe and disposed it into test tube ENB. 4. We inverted twice to mix the ENB test tube.

5. We disposed the contents of test tube SPNB into ENB using a disposable transfer pipet and inverted twice to mix the solution 6. In 1 minute intervals, we observed the color changes of the reactions and compared them to the color palette. We did this for 5 minutes.

Part 2
1. We measured 2 mL of diluted hydrogen peroxide (the substrate), 1 mL of guaiacol (the product indicator), and 1 mL of neutral buffer (pH 7) with a syringe and disposed it into tubes 1, 2 , 4, 9, 11, and 12. 2. We measured 1 mL of turnip peroxidase (the enzyme) and 3 mL of neutral buffer (pH corresponding to the test tube number i.e. pH 5 in test tube 5) with a syringe and disposed it into tubes 3, 5, 6, 7, 8, and 10 3. We poured tube 1 with the solution in tube 3 to combine them. We repeated this for all of the tubes. Each of the tubes in step 1 was mixed with a tube in step 3, making there be 6 total test tubes with a solution in it. 4. We observed the test tubes and compared the colors produced from the reaction to the color palette in 1 minute intervals for 5 minutes total.

Part 3
1. We measured 2.5 mL of 0.1% H2O2 {the substrate), 2.5 mL of guaiacol (the product indicator), and 10 mL of neutral buffer (pH 7) with a syringe and disposed it into test tube SPNB. 2. We inverted twice to mix the SPBN test tube.

3. We measured 10 mL of neutral buffer (pH 7) with a syringe and disposed it into test tube ENB. 4. We heated up 2.5 mL of turnip peroxidase (the enzyme) to 100° Fahrenheit and disposed it into test tube ENB. 5. We inverted twice to mix the ENB test tube.

6. We disposed the contents of test tube SPNB into ENB using a disposable transfer pipet and inverted twice to mix the solution. 7. In 1 minute intervals, we observed the color changes of the reactions and compared them to the color palette. We did this for 5 minutes.

Data: Tables and Graphs

Time – Minutes
pH – Percent
1
60%
2
70%
3
80%
4
90%
5
90%
Rate
0.75
Part 1

Part 2
Minutes
Tube #3
Tube #5
Tube #6
Tube #7
Tube #8
Tube #10
1
40%
70%
60%
60%
50%
0%
2
40%
80%
70%
70%
60%
10%
3
50%
90%
80%
80%
60%
10%
4
60%
100%
80%
80%
70%
10%
5
70%
100%
90%
90%
80%
10%

Part 3
Minutes
pH Level
1
30
2
40
3
40
4
50
5
50

Conclusion

Part 1
In conclusion, we wanted to know if oxygen would be produced if we combined a substrate, enzyme, and neutral buffer. We thought if all substrates reacting with an enzyme create a reaction, then there would be oxygen produced because all reactions have a product created. Data shows that there was oxygen produced and it was produced at a rate of 0.75, or 75% every minute. The rate was steadily going up until after 4 minutes. The percent of pH from 4 minutes to 5 minutes stayed at 90%. If we could change anything about this experiment, we would have measured the substrate, enzyme, neutral buffer, and product indicator more precise because there was an air bubble when we measured our desired amount with a syringe. Part 2

In conclusion, we wanted to know if the different pH levels affected the percent of oxygen produced in the reaction. We thought if we had to specifically use a neutral buffer with a pH of 7 in part 1, then it would affect the percent of oxygen produced because the different pH levels have a different stabilizing effect. Data shows that different pH level do affect the percent of oxygen produced. pH 10 created the least amount of oxygen (10%) and pH 3 produced the next least amount of oxygen (70%). The graph above was kind of like a hill and not a line going up or down, so we thought the farther away from pH 6 or pH 7, the less of a reaction it would have. We thought it was both pH 6 and pH 7 because we researched what a neutral buffer of pH 7 does, and it neutralizes the Part 3

In conclusion, we wanted to know if the temperature of the enzymes would affect the reaction rate. We thought if the temperature was increased to 100° Fahrenheit, then the reaction rate would be slowed, if not completely stopped because its function range. Data shows that the rate of the enzyme reaction was significantly slower when heated up to a higher temperature than when it was cold, the transition to one pH percent to the next took longer. For example, it took 2 minutes for the pH percent to go from 40 to 50, compared to part 1, where it would take a minute to change to the next pH percent. The rate was 0.5, or 50% every minute, compared to 75% every minute, as seen in part 1. If we would change anything about this experiment we would use Celsius instead of Fahrenheit, as the converting from 100° Fahrenheit to 38° Celsius could’ve thrown off our experiment, because had to round the number and it’s a harder number to get an exact reading on the thermometer.

Possible Sources of Errors
Part 1
Possible errors could have been: inaccurate measuring of the substrate, enzyme, neutral buffer, and/or product indicator, not comparing the reactions to the color palette at exact time and comparing it wrong.

Part 2
Possible errors could have been: putting the wrong pH levels in the wrong test tubes, inaccurate measuring of the substrate, enzyme, neutral buffer and/or product indicator, comparing the test tube reactions at different times (for example: we compared test tube 3 to the color palette first and by the time we got to the other test tubes, some time has passed and it wasn’t exactly at the minute), and poor judgment on comparing the reactions to the color palette.

Part 3
Possible errors could have been: inaccurate measuring of the substrate, enzyme, neutral buffer, and/or product indicator, not heating the enzymes at exactly 100° Fahrenheit (since the thermometer was in Celsius and we had to convert it to 38° Celsius), comparing the reactions to the color palette too early or too late, and poor judgment on comparing the reactions to the color palette.

Part 2 Assessment Questions
1. The more neutral the pH level, the higher the reaction rate. I think it occurs because enzymes have a small range to maintain equilibrium. Therefore, changes in the pH, being more acidic or basic, affect it. 2. It reacts with the substrate, because it is an enzyme – it created more oxygen in the tube but the enzyme stayed the same because they don’t change in reactions. 3. It is depended on what we take out, all chemicals are needed to make the reaction happen. If we took some of one chemical out it wouldn’t affect it as much as much as if we took all of one out. If enzyme was taken out, the reaction wouldn’t happen because there would be nothing for the substrate to react with. If we took the substrate, nothing would react with the enzyme. If the indicator was taken out, we wouldn’t see the reaction. 4. Other factors that influence enzyme activity are temperature, substrate, and exposure to light. pH affects it because the more neutral the pH, the more reactant it is compared to if the pH was more acidic or basic. 5. Enzymes that break down food in your mouth and waste in your intestines. 6. The peroxidase from a mammal may be more active because a mammal is more complex than a turnip.

Cite this AP Investigation Lab #13 Enzyme Activity

AP Investigation Lab #13 Enzyme Activity. (2016, Jun 22). Retrieved from https://graduateway.com/ap-investigation-lab-13-enzyme-activity/

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