Introduction:
Most enzymes function by weakening bonds which then in turn lowers the activation energy needed for a reaction to take place. Enzymes, by doing this, can speed up reactions to up to thousands of times faster. Enzymes are specific to what they catalyze, and this means that usually an enzyme can only catalyze one substance. Since enzymes speed up reactions by weakening bonds, there is also variables that can further increase the rate at which an enzyme functions. There are four; temperature, pH, enzyme concentration, and substrate concentration. Keeping this in mind, we wanted to know how enzyme concentration directly affects the rate of a reaction. To find the answer, first we first we developed a hypothesis. We hypothesized that a higher enzyme concentration would result in a higher rate of reaction. Then we designed our experiment in order to directly test the variable. We used a natural enzyme found in plants called peroxidase and the substrate that is hydrogen peroxide. To test our hypothesis, we made five different concentrations of the enzyme and added the substrate to it. We the recorded what we saw.
Purpose: The purpose of our experiment was to test whether or not a higher enzyme concentration would result in a higher rate of reaction and more product being produced.
Hypothesis: If a higher enzyme concentration results in a higher rate of reaction, then it will result in more product from the catalytic reaction.
Procedure:
Materials:5 glass test tubes
Test tube rack/Holder
Fresh picked grass
Water
Mortar and pestle
Hydrogen peroxide
10 mL syringe
Small ruler
Safety glasses
1 paper towel for filtration
Digital Balance
Cell phone timer
Steps:
Weight 3 grams of grass on digital balance
Put grass in mortar with water
Grind grass keeping a 3 gram to 10 mL of water ratio
Filter enzyme using paper towel
Put 5 test tubes on test tube rack
Make five different concentrations of enzyme by diluting with water in test tubes
Measure 1 mL of Hydrogen peroxide
Put safety glasses on
Put Hydrogen Peroxide in each concentration one by one
Record product produced over the span of 1 minute by using small ruler
Results:
Sec | Concentration
|
20%
|
40%
|
60%
|
80%
|
100%
|
10 seconds
|
0.5
|
0.7
|
1.0
|
2.5
|
2.9
|
20 seconds
|
0.9
|
1.2
|
1.8
|
4.0
|
5.2
|
30 seconds
|
1.4
|
1.8
|
2.7
|
5.3
|
7.1
|
40 seconds
|
1.7
|
2.3
|
3.5
|
6.4
|
8.5
|
50 seconds
|
2.0
|
2.9
|
4.2
|
7.1
|
9.7
|
60 seconds
|
2.6
|
3.4
|
4.9
|
7.8
|
10.7
|
Data Analysis:
Out of the five concentrations, all reactions produce product. However, the highest enzyme concentration produced the most product due to it's faster rate of reaction, and so on. The concentration that was 3 mL enzyme and 0 mL water produced 10.9 cm of product, the concentration that was 2.4 mL enzyme and 0.6 mL water produced 7.8 cm of product, and the concentration that was 1.8 mL enzyme and 1.2 mL water produced 4.9 cm of product. Finally, the concentration that was 1.2 mL enzyme and 1.8 mL water produced 3.4 cm product and the concentration that was 0.6 mL enzyme and 2.4 mL water produced 2.6 cm of product. This line graph correctly displays our data because it shows a line for each concentration with its product at every 10 seconds and the final amount it produced. The chart explains product being produced by each concentration over the course of one minute as well. We created the graph to display that yes, a higher enzyme concentration does result in a higher rate of reaction and more product being produced. We also created it to display a "total" amount of product produced from each concentration.
Conclusion:
In this experiment, we were given the four variables that affect the rate of reaction between an enzyme and substrate, temperature, pH, enzyme concentration and substrate concentration. From these four, we had to formulate a hypothesis and create a experiment testing the effect that the variable has on the rate of reaction. We chose to conduct our experiment on enzyme concentration. Specifically, how enzyme concentration would affect the rate of reaction and the product being released by the enzyme and the substrate. We hypothesized that if enzyme concentration has an effect on the rate of reaction, then the higher the concentration, the higher the rate of reaction will be and the more product it will produce from the reaction. For the design of our experiment, we decided to have the same volume of enzyme in 5 different trials, but have each diluted with water by 20%, increasing by each trial. We had 5 trials in total, meaning we had one concentration that was 3 mL enzyme and 0 mL diluted with water, one that was 2.4 mL enzyme and 0.6 diluted with water, one that was 1.8 mL enzyme and 1.2 mL diluted with water, one that was 1.2 mL enzyme and 1.8 mL diluted with water, and finally, one that was 0.6 enzyme and 2.4 diluted with water. From then, we added 1 mL of hydrogen peroxide to each concentration and recorded the results we observed. We recorded each concentration for a minute, and measured the product it produced using centimeters. We recorded that the concentration with 100% enzyme produced 10.7 cm of product, the 80% enzyme and 20% water produced 7.8 cm of product, the 60% enzyme and 40% water produced 4.9 cm of product, the 40% enzyme and 60% water produced 3.4 cm of product, and finally, the 20% enzyme and 80% water produced 2.6 cm of product. From this, we notice something that could be a correlation to what we hypothesized.
In the data we retrieved, we see that the as the enzyme concentration increases, the product being produced increased as well. These results indicate that, in support of our hypothesis, a higher enzyme concentration did in fact result in a higher rate of reaction and more product being produced. With an increased enzyme concentration, came an increased amount of product being produced from the reaction. We believe that these result suggest that yes, a higher enzyme concentration does result in a higher rate of reaction overall. Of course, if this is true, then a lower enzyme concentration in turn results in a lower rate of reaction. These were the results we expected to get because we knew that if there is a higher enzyme concentration, then there is more enzyme to attach to the substrate, which then in turn results in more product being produced which indicates a higher rate of reaction. We anticipated these results because it is a scientific fact that a higher enzyme concentration results in a higher rate rate of reaction. Our findings are significant because they show support to our hypothesis and display support to previously stated scientific information. Our findings connect to the real world because, most likely, a type of higher enzyme concentration, no matter the type of enzyme, will be probable to produce a higher rate of reaction. Based on our findings, scientific information, and the manner in which we conducted our experiment, anyone should be able to re-create our experiment and get similar findings.
While we conducted our experiment, our minds were running all over the place, asking all types of questions related to the experiment. One of the most significant questions that came to mind happened to be, what would happen if substrate concentration was the one being increased instead of enzyme concentration? We came to the conclusion that if substrate concentration were being increased, it would show similar results to that of increased enzyme concentration, but certainly not identical. The graph of the increased substrate concentration would have a “leveling off” as it reaches maximum activity. Our experiment was not necessarily conducted in the most efficient manner, but it was the most efficient manner we would get it to at the moment. If we could go back, we would change the volume of the enzyme concentration in each test tube. This was because as the concentrations increased, it got more and more difficult to measure the product being produced as it began to overflow. This was about the only difficulty we encountered, but we used our problem solver minds to solve the problem. To keel measuring after it overflowed, we just measured how much would come out of the top of the test tube. Another minor thing that went wrong was that, when we were trying to filter our enzyme with a paper towel, the paper towel absorbed everything, and we had to make a new batch of enzyme. Other than those two explained, our experiment ran pretty smoothly.
Bibliography:
“Grass .” WHYY, whyy.org/episodes/grass-wars-bermuda-vs-fescue/.
“Hydrogen Peroxide.” Target, www.target.com/p/hydrogen-peroxide-topical-solution-usp-32oz-up-up-153/-/A-15115908.
Test Tube Rack. www.fishersci.com/shop/products/locking-test-tube-rack-blue/14955035.
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