Enzyme Lab Introduction/ Abstract An enzyme is a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction. They are mainly made up of proteins and can tremendously speed up reactions. E. coli ( a bacterium) has about 1,000 different types of enzymes floating around in its cytoplasm at any given time. Enzymes can be used to join and even break up molecules as shown in the diagram below. (1) A maltose molecule is about to go into an maltase enzyme which are shaped to fit maltose molecules perfectly. 2) The molecule enters the enzymes active site and prepares to be broken down. (3) The maltose molecule’s bonds are broken down to produce 2 glucose molecules which then proceed to leave the enzyme. We will be investigating an enzyme in this experiment. Catalase to be more specific which is found in the liver. We will compare its action under different conditions with an inorganic catalyst called manganese dioxide. Purpose The purpose of performing this lab is to compare the action of catalase to a non-protein catalyst under different conditions.
Hypothesis In section A, I hypothesize that the sand will have no reaction but the MnO2 will produce a gas or start to foam up. In section B, I suspect that the liver may start to show signs of deformation or shrink in size. The potato will foam up like the liver in section A. In section C, I think there will be no reaction for either substances. Both liver will most likely start to foam up in section D. Finally, in section E, the boiled liver will produce no reaction but the other 2 will most likely have a reaction where bubbles are produced.
Materials Materials: * 3% hydrogen peroxide * Manganese dioxide * Fresh or frozen liver * Potato * Ice Equipment: * Fine clean sand * Stirring rod * Bunsen burner or hotplate * 250mL beaker * test tubes * scalpel Method A. Catalytic reactions 2 ml of hydrogen peroxide was added to two test tubes. 0. 1g of sand was placed in one test tube and o. 1g of manganese dioxide was added to the second tube. The reaction was then observed and recorded. B. The effect of an enzyme 2 ml of hydrogen peroxide was added to each of two clean test tubes.
A small piece of liver was placed into one of the test tubes and in the other, a small piece of potato. The results were then recorded and compared with the results from the manganese dioxide. We then put the materials to the side. C. Re-using an enzyme The liquid portion of the previous tube in B were divided containing the liver into two test tubes. The liver from procedure B was cut into two equal portions and added to two test tubes. Then a fresh piece of liver was added to the first test tube and 1 ml of hydrogen peroxide was added to the second tube.
The results were then recorded. D. Effect of particle size A small piece of liver was placed in one test tube and a small piece of potato was placed in a second tube. A pinch of sand was added to each test tube and crushed with separate stirring rods. 2 ml of hydrogen peroxide was added to each tube, then the rates of the reactions were observed and recorded. The results were then compared with the results of the uncrushed liver and potato in part b. E. Effect of temperature A small piece of liver was placed into a test tube and was heated for 5 minutes in a boiling water bath. ml of hydrogen peroxide was added to the boiled liver and the results were recorded. A small piece of liver was placed into each of two test tubes. One test tube was placed into a 37oC water bath for 5 minutes and the second tube was placed in an ice-water bath for the same length of time. 2 ml of hydrogen peroxide was added to each test tube. The rates of reaction were then recorded. Observation Table Enzyme Lab Table Section| Situation| Observations| Interpretation| Rate of Reaction| A| Sand| Sand sunk, nothing else happened. There was no reaction. | 0| | MnO2| Black bubbles formed producing a popping noise. The test tube got colder. | A reaction occurred. | 2| B| 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| 1.
5| C| Used liver + Fresh liver| Nothing happened, the water got dirty from the decomposing liver. The contents also gave off a metallic scent. | There was no reaction. 0| | Used Liver + H2O2| Large bubbles formed, the test tube got warmer and the liver became suspendded. The test tube also gave off a metallic scent. | There was a large reaction. | 4| D| Crushed liver| The test tube got warmer. Many bubbles formed, there was a strong metallic odour. The bubbles are polygonal. | There was a rapid reaction. | 4| | Crushed potato| Foam formed. the sand begun to rise, the water got cloudy, there was a slightly sweet scent and the test tube got warmer. | A mild reaction occurred. | 3| E| Boiled liver| No reaction, the liver was charred. | There was no reaction. 0| | Liver at 37oC| The water got cloudy, the liver was floating, and bubbles formed. | Best reaction out of all three in section E| 3| | Liver at 0oC| The water got cloudy, the liver began to float and a couple of bubbles began to form. | There was a slow reaction| 1. 5| Error Analysis During this experiment, a couple of errors were made on our part. For one, the livers weren’t cut out to be the same size which may have skewed the results. The second error would be something we couldn’t really prevent. It is that the scale was up to our interpretation meaning it wasn’t persistent.
Questions 1. How do you account for the differences in the rates? The reactions where the rate of reaction was a 4 had hydrogen peroxide involved in the reaction. This is because catalase and hydrogen peroxide were involved in the reaction. When catalase comes in contact with hydrogen peroxide, the hydrogen peroxide turns into water and oxygen gas. The foam is pure oxygen bubbles created by the catalase and since it is an enzyme, this reaction is done extremely efficiently (up to 200,000 reactions per second! ). The potato and liver both contain catalase cells. he reactions where the rate of reaction were 0 was because there was no reactions that would occur from the reactants that were put into the test tubes. 2. Can H2O2 be broken down by catalysts other than those found in living systems? Explain your answer. Yes it can be. Hydrogen peroxide and be broken down by oxidization. Inorganic compounds such as ferric chloride and manganese dioxide can achieve this. 3. Describe the effect of temperature and particle size on the rate of enzyme action? Temperature can speed up enzyme action if it is warm, if it is cooler then it will slow down enzyme action.
If the particle is small then enzyme action will be fast and if the particle is big then enzyme action will be slower. 4. The body temperature of a dog is approximately 40oC. Would your results be different if you had used pieces of dog liver for this investigation? It wouldn’t make a difference unless the liver was fresh out of a dogs body since it would still be fairly hot. However if it was placed under the same circumstances that the liver we used was under then it would produce the same results since the livers temperature would end up dropping the same temperature as the liver we used.
What would happen if additional hydrogen peroxide were added to the second tube? There would be more foam being produces since there is more reactant to react with the catalase. Conclusion By the end of this lab, I learned a lot about inorganic enzymes and about how hydrogen peroxide reacts with catalase which was found in the liver. A couple of errors were made during the process but in the end we got the just of what each reaction would produce.
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. <http://www. madsci. org/posts/archives/2007-02/1171045656. Ch. r. html>. “HowStuffWorks “Why does hydrogen peroxide foam when you put it on a cut? “. ” HowStuffWorks “Science”. N. p. , n. d. Web. 14 Oct. 2012. <http://science. howstuffworks. com/innovation/science-questions/question115. htm>. “What are Enzymes?. ” wiseGEEK: clear answers for common questions. N. p. , n. d. Web. 14 Oct. 2012. <http://www. wisegeek. com/what-are-enzymes. htm>.