Purpose:
The purpose of this experiment was to observe the conversion of hydrogen dioxide to water and oxygen gas by the enzyme catalase, and measure the amount of oxygen generated and calculate the rate of the enzyme-catalyzed reaction. We basically had to observe and understand the effects of changes in temperature, pH, enzyme concentration, and substrate concentration on the reaction rate of an enzyme-catalyzed reaction, and also to understand how environmental factors affect the rate of enzyme-catalyzed reactions.
Intro:
Enzymes are proteins produced by living cells. They are biochemical catalysts meaning they lower the activation energy needed for a biochemical reaction to occur. The substrate is the substance acted upon in an enzyme-catalyzed reaction, and it can bind reversibly to the active site of the enzyme. The active site is the portion of the enzyme that interacts with the substrate so that any substrate that blocks or changes the shape of the active sit effects the activity of the enzyme. The result of this temporary union is a reduction in the amount of energy required to activate the reaction of the substrate molecule so that products are formed. The enzyme is not changed in the reaction and can be recycled to break down additional substrate molecules. The enzyme used in this lab is catalase. One catalase function is to prevent the accumulation of toxic levels of hydrogen peroxide formed as a by-product of metabolic processes. The decomposition of hydrogen peroxide to form water and oxygen: 2 H2O2 → 2 H2O + O2 (gas) Without catalase this reaction occurs spontaneously but very slowly. Catalase speeds up the reaction notably.
Methods:
For each solution a 5mL sample was taken and put it into a fresh beaker and added drops of KMnO4 until the solution became colored.
Data
The purpose of this experiment was to observe the conversion of hydrogen dioxide to water and oxygen gas by the enzyme catalase, and measure the amount of oxygen generated and calculate the rate of the enzyme-catalyzed reaction. We basically had to observe and understand the effects of changes in temperature, pH, enzyme concentration, and substrate concentration on the reaction rate of an enzyme-catalyzed reaction, and also to understand how environmental factors affect the rate of enzyme-catalyzed reactions.
Intro:
Enzymes are proteins produced by living cells. They are biochemical catalysts meaning they lower the activation energy needed for a biochemical reaction to occur. The substrate is the substance acted upon in an enzyme-catalyzed reaction, and it can bind reversibly to the active site of the enzyme. The active site is the portion of the enzyme that interacts with the substrate so that any substrate that blocks or changes the shape of the active sit effects the activity of the enzyme. The result of this temporary union is a reduction in the amount of energy required to activate the reaction of the substrate molecule so that products are formed. The enzyme is not changed in the reaction and can be recycled to break down additional substrate molecules. The enzyme used in this lab is catalase. One catalase function is to prevent the accumulation of toxic levels of hydrogen peroxide formed as a by-product of metabolic processes. The decomposition of hydrogen peroxide to form water and oxygen: 2 H2O2 → 2 H2O + O2 (gas) Without catalase this reaction occurs spontaneously but very slowly. Catalase speeds up the reaction notably.
Methods:
First we put 10 mL of 1.5% H2O2, and then added 1 mL of catalase extract and swirled it gently for 10 seconds. At 10 seconds,we added 10 mL of H2SO4. The same thing was done six more times but with intervals of 30, 60, 90, 120, 180, and 360 seconds before adding the H2SO4.
For each solution a 5mL sample was taken and put it into a fresh beaker and added drops of KMnO4 until the solution became colored.
Data
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| Finding our baseline (uncatalyzed) reading |
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| *note our 10 second trial is miscalculated due to our error |
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Graph |
Discussion
The rate of the reaction is calculated by measuring, over time, the disappearance of the substrate, which can be measured by seeing when the appearance changes of the product. The rate, in the experiment, is the highest from the initial to ten, because the hydrogen peroxide had been exposed to the air for the least amount of time. It's lowest rate was when the hydrogen had been exposed to the air longer. This is because the longer the hydrogen peroxide is exposed to air the more broken down it becomes, and therefore, weaker. The sulfuric acid has an inhibiting effect on the catalase's function because it causes the pH level in the solution to lower a considerable amount. Acidic solutions result in the protein structure of the enzyme to gain hydrogen ions which causes it to denature, which stops the reaction immediately. Lowering the temperature in this experiment would cause the reaction to slow down due to enzymes working best in normal temperature. If the temperature were lowered a larger amount, for example lower than 37 degrees celcius, it would be denatured and not be able to react anymore. Although this experiment was as controlled as possible, several things could have been controlled better. In some instances, too much KMnO4, resulting in a redo. Watching the reaction of the solution to the KMnO4 is not very controlled due to the fact that different people see different things. What one person sees as a change of color another may not.
Conclusion
This lab presents how changes in temperature, pH, substate concentration and enzyme concentration can effect the reaction rate of an enzyme catalyzed reaction. Our observations of the amount of oxygen produced in comparison to the rate of the enzyme catalyzed reaction showed how the environment can drastically effect the rate of the reaction. .
Nice job - please include captions under each of the pictures to help guide the read through the experiment.
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