The Effect of Substrate Concentration, Enzyme Concentration, Ph and Temperature on Enzyme Activity”

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Title: “The Effect of Substrate Concentration, Enzyme Concentration, pH and Temperature on Enzyme Activity”

In the following experiments we will measure precise amounts of potato extract as well as Phenylthiourea, combined with or without deionized water and in some instances change the temperature and observe and record the reaction. We will also investigate the different levels of prepared pH on varying samples of the potato extract and the Phenylthiourea and record the results. We will answer question such as what is the best temperature for optimum temperature reaction as well as the best pH level for the same reaction.

This experiment will entail several areas the first to be investigated will be what are the effects of substrate concentration on enzyme activity. We will only use to different samples in an effort to save time and record the results. In our initial predictions we felt that “If we added more of the substrate the enzyme reaction should be instant.” Of course the following data is aimed to prove or disprove this or at least aim to bring about data to support the answers.

Hypothesis: Enzyme activity can be changed by substrate concentration and enzyme concentration as well as certain pH and temperature changes.

After carefully measuring and recording the different levels of substrate and enzyme we recorded all the data that corresponded to the change after the level of catechol was changed as well as observing the different pH on the same enzyme.

Materials List
1. Test tubes
2 .Test tube rack
3. Small Para film squares
4. Distilled water
5. Potato extract
6. Catechol
7. Phenylthiourea
8. Disposable gloves
9. Pipette 5ml
10. Pipette 1ml
11. Bunsen burner
12. Ice
13. Ice chest
14. Thermometer
15. pH solutions

Patricia Marcel
Biology 1111-17
Lab # 7 Enzymes
Table 2B
The Effect of Substrate Concentration on Enzymes Activity
TubesdH20Potato extractCatecholObservations
1500µl + 5ml500µl500µlDark yellow
2900µl + 5ml500µl100µlYellowish pinkish

The lower the enzyme concentration the less enzyme activity was seen but the reaction in tube # 1 exhibited the opposite behavior since it had a higher enzyme.

Table 2 C
The Effect of Enzyme Concentration on Enzyme Activity
TubedH2OPotato extractCatecholObservations
1500µl + 5ml500µl500µlAmber
2500µl + 5ml100µl100µlLight Yellow

The catechol increase in the tube # 1 brought about a quicker reaction than the reaction in the tube # 2, which proved that the tube with the most catechol had the greatest and quickest reaction level as evident in the color change.

Patricia Marcel
Biology 1111-17
Lab # 7 Enzyme

Table 2D
The Effect of pH on Enzyme Activity
Buffer pHBuffer volumedH2OCatecholPotato extractObservation 42ml3ml500µl500µlclear

After examining the different levels of buffer solution we saw a reaction in all the tubes except for the tube that had pH of 4. This signaled that the buffer solution was at a neutral level and could not react with the substrate. The tube with a buffer level of pH of 8 proved to be the best buffer since the solution turned dark orange.

Table 2 E
Tubes (temperature)dH20CatecholPotato ExtractObservations 1(0˚C)5ml500 µl500 µlyellow
2(15˚C)5ml500 µl500 µlyellow
3(35˚C)5ml500 µl500 µlorange
4(100˚C)5ml500 µl500 µlpink

Each tube in this part of the experiment showed some level of reaction, the results went against what I speculated which was that extreme temperatures would cause a better reaction. Instead we saw that once the temperature reached 100˚C the reaction did not react well. But at the temperature of 35˚C the reaction was the greatest because the color changed to a bright orange color....
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