The purpose of this lab is to compare the action of catalase, an enzyme found in the liver, to that of a non-protein catalyst called manganese dioxide. Enzymes are substances produced by living organisms that act as catalysts for specific biochemical reactions. They are mainly composed of proteins and can significantly accelerate reactions. Within the cytoplasm of the bacterium E. coli, there are about 1,000 different types of enzymes present at any given time. Enzymes have the ability to join and break up molecules, as depicted in the diagram below.
In this experiment, we will investigate an enzyme called maltase which has a shape perfectly suited for breaking down maltose molecules into two glucose molecules. We will explore how catalase compares to manganese dioxide under various conditions.
Hypothesis: In section A, the sand will not react, but the MnO2 will generate a gas or foam up. In section B, it is believed that the liver may exhibit signs of deformation or shrink in size. The potato will foam up similar to the liver in section A. In section C, no reaction is expected from either substance. Both livers will probably foam up in section D. Finally, in section E, the boiled liver will not produce any reaction, but the other two substances will likely produce bubbles.
The experiment required the following materials: 3% hydrogen peroxide, manganese dioxide, fresh or frozen liver, potato, and ice. The equipment needed included fine clean sand, a stirring rod, a Bunsen burner or hotplate, a 250mL beaker, test tubes, and a scalpel.
For the first part of the experiment on catalytic reactions, one test tube was filled with 2 ml of hydrogen peroxide and 0.1g of sand while another test tube contained 2 ml of hydrogen peroxide mixed with 0.1g of manganese dioxide. The observations and recordings were made for these reactions.
Moving on to the second part which focused on the effect of an enzyme, two separate clean test tubes were used. In each test tube there were 2 ml of hydrogen peroxide.
Two test tubes were used in this experiment. In one test tube, a small piece of liver and a small piece of potato were placed. The results obtained from this test tube were compared with the results obtained from manganese dioxide. Afterward, these materials were set aside.
In the other test tube, the liquid portion of the previous test tube that contained the liver was divided into two parts. The liver that was used before was cut into two equal portions and added to these test tubes. Furthermore, a fresh piece of liver was added to the first test tube, while 1 ml of hydrogen peroxide was added to the second test tube.
The investigation focused on the effect of particle size by conducting various experiments. In one experiment, a small piece of liver was placed in a test tube and a small piece of potato in another. Both tubes were mixed with sand, which was then crushed using separate stirring rods. After adding hydrogen peroxide to each tube, the rates of the reactions were observed and recorded. The results were compared with those from uncrushed liver and potato experiments conducted earlier.
In addition to particle size, temperature was also studied. One experiment involved heating a small piece of liver in boiling water for 5 minutes before adding hydrogen peroxide and recording the results. Another experiment involved placing a small piece of liver into two test tubes: one at 37°C and the other in an ice-water bath for 5 minutes. Hydrogen peroxide was added to both tubes, and the rates of reaction were noted down.
Summary Table:
| Section | Situation | Observations | Interpretation |
|———|————–|——————————————————————|—————-|
| A | Sand | The sand sunk without any further reaction | – |
| – | MnO2 | Black bubbles formed with a popping noise; Test tube got colder | A reaction occurred| | Quantity Item Observation | |
| — | — | — |
| 2 | Liver | Foam formed, large bubbles formed, test tube was warm, the liver was suspended in the test tube and wrinkled. A reaction occurred.|
| 3.5 | Potato | White foam, small bubbles formed producing a popping noise. Small reaction occurred.|
5| C| Used liver + Fresh liver| When the fresh liver was decomposed, the water became dirty and emitted a metallic scent.
0| | Used Liver + H2O2| A large reaction occurred when the liver was suspended in H2O2, as large bubbles formed, the test tube got warmer, and a metallic scent was emitted.
4| D| Crushed liver| There was a rapid reaction when the crushed liver was placed in the test tube. The test tube got warmer, polygonal bubbles formed, and a strong metallic odor was detected.
4| | Crushed potato| A mild reaction occurred when the crushed potato was added to the test tube. Foam formed, sand rose, water became cloudy, and there was a slightly sweet scent. The test tube also got warmer.
3| E| Boiled liver| No reaction occurred; instead, the boiled liver turned charred.
0| | Liver at 37oC| The best reaction out of all three in section E happened with the liver at 37°C. The water became cloudy, the liver floated, and bubbles formed.
1. 5| Liver at 0oC | There was a slow reaction when using liver at 0°C. The water became cloudy, the liver began to float,and a couple of bubbles formed
In this experiment multiple errors were made on our part: firstly,the livers were not cut to be equal sizes which may have skewed results; secondly,the measurement scale used lacked consistency due to our interpretation.
The involvement of hydrogen peroxide can explain the differences in reaction rates. When catalase and hydrogen peroxide interact, the hydrogen peroxide is converted into water and oxygen gas, resulting in foam. The catalase enzyme efficiently facilitates this reaction at a rate of 4 reactions per second or up to 200,000 reactions per second. Both potato and liver contain cells that possess catalase. Conversely, reactions with a rate of 0 occurred because there were no possible reactions with the given reactants in the test tubes.
Other catalysts besides those found in living systems, such as oxidization, can also break down hydrogen peroxide (H2O2). Inorganic compounds like ferric chloride and manganese dioxide have the ability to break down hydrogen peroxide.
The rate of enzyme action is influenced by temperature and particle size. Warm temperatures accelerate enzyme action while cooler temperatures slow it down.
If the particle size is small, enzyme action will be faster. Conversely, if the particle size is large, enzyme action will be slower. The body temperature of a dog is around 40oC. If we used pieces of dog liver for this experiment, the findings would remain unchanged unless the liver was freshly removed from a dog’s body. In that scenario, it would still be relatively warm. Nevertheless, if the liver was subjected to identical conditions as the one we utilized, it would yield comparable outcomes as its temperature would eventually decrease to match that of our specimen.
Adding more hydrogen peroxide to the second tube would result in an increased foam production. This is because there is a higher amount of reactant available for the catalase to react with. In conclusion, this lab provided valuable knowledge on inorganic enzymes and the reaction between hydrogen peroxide and catalase found in the liver. Despite a few errors during the process, we still obtained a general understanding of the products produced in each reaction.
Works Cited Free, David. “Re: Can H2O2 be broken down by catalysts other than those in living systems?. MadSciNet: The 24-hour exploding laboratory.. N. p. , n. d. Web. 14 Oct. 2012.
. “HowStuffWorks “Why does hydrogen peroxide foam when you put it on a cut? “. ” HowStuffWorks “Science”. N. p. , n. d. Web. 14 Oct. 2012.
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