How Hydrogen Peroxide Affects the Rate of Reaction of the Enzyme Catalase
Introduction:
Catalase, like all enzymes, is made up of protein molecules. It can be found in the cytoplasm of living tissue. It speeds up the decomposition of Hydrogen Peroxide, a metabolic waste product, into water and oxygen that can safely be removed from the cell.
The type of reaction involved is known as a catabolic reaction (i.e. substrate broken down.)This is simply because the substrate enters the active site and is broken down, and leaves as 2 separate products, in this case water and oxygen:
2H2O2> 2H20 + O2
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Like all enzymes, the rate at which the enzyme works is affected by many variables.
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The maximum produced in my second experiment was 2.6. But this can be explained by how long the enzyme had to react. It takes much longer to reach maximum velocity with a competitive inhibitor present and therefore I believe that if I had left the experiment going the same levels of oxygen would have been produced as in the first experiment. These findings follow my prediction, other than the 90% readings. According to my prediction, even with an inhibitor present the 90% concentration readings should have been higher than the 80% concentration readings. As stated above this could be because that the enzyme concentration is the limiting factor. But the figures actually drop from 80% concentration to 90%. This could be explained because there are so many substrate molecules competing for the active sites of the enzyme molecules that they actually start to block the site. Therefore there is a slight decrease in oxygen produced.
I believe that the inhibitor in the nitrate solution was a competitive one. This because if it was a non-competitive the reaction rate would have risen as concentration rises only for a short while, and then
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(see evaluation)
Evaluation:
My experiment went very well and I got a good set of results, which I could base my conclusion on.
The accuracy and observations of my experiment, I felt was consistently good. All of my readings were to a degree of accuracy that I felt was adequate. All weight measurements of the celery were 3g, +/- 0.15g. I felt this was accurate enough for my purposes; a size difference of 0.3g at the most would not have made considerable difference. My measurements of oxygen given off were all to 0.1 cc and throughout my experiment I used the most accurate glass measuring cylinder available.
I did not have many anomalous results. But both experiment numbers 2, in the two variable tests (shown in red in the results table) seem to be of a generally lower value than results 1&3. Both these experiments were carried out on the same day. There could have been a number of reasons why these anomalous results occurred:
* My teacher supplied the celery I used for my experiments. It had been purchased from various supermarkets in the area. It
More hydrogen ions in a solution is a result of lower pH, while fewer hydrogen ions in a solution is a result of increased pH. Meaning that a lower pH level results in a higher enzyme activity reaction and a higher pH level results in a lower enzyme activity reaction (Christianson, 2011 ).
Cut a 5 cm length of celery stem 2. Cut through the grooves to divide the stem into thin strips 3. Dry the cell sap from the strips using a paper towel 4. Record and note the mass of each strip 5. Collect 6 test tubes, and put 10 cm³ of solutions 0.0, 0.1, 0.2, 0.3, 0.5, 0.7, 0.8.
This enzyme speeds up the break down of hydrogen peroxide into water and oxygen, as enzymes are biological catalysts. [IMAGE]The reaction: Hydrogen peroxide Water + Oxygen Catalase -------- [IMAGE] 2H2O2 2H2O + O2 Apparatus: Hydrogen Peroxide, Several sticks of celery, Stand, boss and clamp, 100ml conical flask, 25cm3 burette, 1800cm3 beaker, Rubber bung with delivery tube, Distilled water, Large container filled with water, 10cm3 measuring cylinder, 10cm3 syringe, 20cm3 syringe, Blender, Knife, Ceramic tile, Electronic balance (correct to 2 decimal places), Sieve, Stopwatch/timer. The variables: There are many possible variables in this investigation, such as pH, temperature, the concentration of substrate and the concentration of the enzyme.
The reaction will increase with the increasing enzyme concentration when the molecules of hydrogen peroxide are freely available. The more concentrated the catalase the more chance of the
being used up, for that is a property of a catalyst is, it speeds up a
In this experiment the enzyme peroxidase and the substrate hydrogen peroxide were not mixed initially, instead they were both placed in separate tubes and were incubated at a specific temperature, to prevent hydrogen peroxide from undergoing any reaction with peroxidase until they both acquire the required temperature.
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
From looking at the results I can conclude that when the pH was 3 and 5. No oxygen was produced, therefore no reactions were taking place. This was because the pH had a high hydrogen ion content, which caused the breaking of the ionic bonds that hold the tertiary structure of the enzyme in place of the syringe. The enzyme lost its functional shape.
oxygen. Before I do this I must do a preliminary plan to see what my
Purpose: The purpose of this lab is to explore the different factors which effect enzyme activity and the rates of reaction, such as particle size and temperature.
... point was subjective; however it would have been a systematic error because I consistently judged the end point of my experiment. To eliminate this inaccuracy I should have used a colorimeter to judge the end point of my experiment.
This is because there is more hydrogen peroxide to be broken down by the enzyme and with more hydrogen peroxide in the reaction, more oxygen is released.
an enzyme is used to speed up the process in the equation above. In my
Chemical Kinetics is the branch of chemistry that studies the speed at which a chemical reaction occur and the factor that influence this speed. What is meant by the speed of a reaction is the rate at which the concentrations of reactants and products change within a time period. Some reactions occur almost instantaneously, while others take days or years. Chemical kinetics understanding I used in the process of designing drugs, controlling pollution and the processing of food. Most of the time chemical kinetics is used to speed or to increase the rate of a reaction rather than to maximize the amount of product. The rate of a reaction is often expressed in terms of change in concentration (Δ [ ]) per unit of time (Δ t). We can measure the rate of a reaction by monitoring either the decrease in concentration (molarity) of the reactant or the increase in the product concentration.
The Concentration of Hydrogen Peroxide and Speed of The Rate at Which It is Broken Down by Catalase