Catalysts are substances that increase chemical reactions while using less energy. They also remain unchanged after use, which enables it to be used repeatedly. Cells have special catalysts called enzymes, which are specialized proteins that help accelerate chemical cell reactions. (Evert, RF & Eichhorn, SE 2013). Enzymes also control plant metabolic processes such as respiration (Evert RF, Eichhorn SE & Perry JB 2013). This experiment focuses on the enzyme catalase. Catalase breaks down hydrogen peroxide into water and oxygen.
Hydrogen peroxide is a waste product of cell metabolism that can be toxic to the cell (Evert RF, Eichhorn SE & Perry JB 2013). The enzyme catalase can be found in the peroxisomes of plant cells (Willekens, H, Inze, D, Van Montagu, M & van Camp, W. 1995). One can conclude that the oranges have some catalase present. Potatoes on the other hand have catalase in their cell wall and golgi bodies (Brinkman, FG & Sminia, T. 1977). These two can then be compared and shouldn’t have a significant difference between the rates of catalase activity. Several methods have been used to measure catalase activity.
Some studies have used sophisticated methods such as measuring oxygen manometrically and via polarography (Beers, RF & Sizer, IW. 1951). For this experiment, the rate of catalase activity is measured simply by timing how long a filtered disc dipped in the plant solution will float to the top. Since catalase breaks down hydrogen peroxide into water and oxygen. The filtered disc will float to the top due to the release of oxygen. The objective of this study is for students to observe how enzymes such as catalase aid in metabolic processes. This also enables students to investigate what factors can affect catalase activity.
Students are allowed to change certain variables specified by the instructor to compare with those of the potato plant. The variable changed in this experiment is the plant material. Instead of a potato, an orange was used. The hypotheses being tested are as follows: 1) The orange will affect the time of catalase activity by increasing the time of catalase activity as compared to the potato. 2) The orange will not affect the time of catalase activity. Materials and Methods This experiment was done in a school laboratory with a partner and the aid of the laboratory professor.
A small amount of potato was grounded with a small amount of pH7 and fine sand. The paste was then placed in a microcentrifuge tube and spun at a high speed. This action separated the catalase containing liquid; this liquid was then transferred to a clean microcentrifuge tube (Evert RF, Eichhorn SE & Perry JB 2013). Several filter paper discs were cut using a hole punch. Using forceps each disc was then dipped into the catalase containing liquid and blotted briefly on a sheet of filter paper. The discs were dropped one by one into a beaker with 10 mL of hydrogen peroxide.
Once the disc hit the bottom of the beaker it was then timed until it floated to the top and then removed. If the disc settles on the side of the beaker, remove the disc and repeat with a new disc. Once ten discs have been dropped and recorded. Replace the old hydrogen peroxide found in the beaker with a new 10 mL of hydrogen peroxide and repeat the same experiment using ground up orange pulp cells (Evert RF, Eichhorn SE & Perry JB 2013). The control treatment of this experiment is distilled water. A filter paper disc is dipped in distilled water and then placed in the beaker of hydrogen peroxide and timed for atalase activity (Evert RF, Eichhorn SE & Perry JB 2013).
Results Table 1. Average Rate of Catalase Activity for a Potato, Orange and the Control group Potatoes had an average rate of catalase activity of 4. 97 seconds while both the control and the orange cells have an average rate of catalase activity of zero seconds. Discussion It is no surprise that there are values associated with the rate of catalase activity in potatoes since it has been pinpointed that catalase enzymes are found in its golgi bodies and cell wall (Brinkman, FG & Sminia, T. 977).
The average rate of catalase activity as seen in the chart above is 4. 97 seconds while the orange is at zero seconds. During the experiment, none of the orange filtered discs rose in the given amount of time. From the data, one can see that the orange has no effect on catalase activity. Therefore the null hypothesis, the orange will not affect the catalase activity is accepted. Errors in the experiment could have come from not having the same amount of pH 7 and fine sand ground with the plant material.
The amount of buffer could have been too little or too much in either plant material. Another source of error is the blotting of excess liquid; excess blotting can lead to loss of the enzyme catalase. Another error is time; more time could have been given to wait for the orange filtered disc paper to rise. To further catalase activity studies, one can compare and contrast other plant species to the potato or keep the potato and change other variables such as the buffer used and/or temperature which has been done by others in the laboratory.
Another experiment could be to pinpoint the location of catalase enzymes in an orange fruit. Conclusion From the results of the experiment above, the catalase activity of the orange fruit is zero seconds while the potato had an average rate of 4. 97 seconds. The orange fruit then in this experiment had no effect on catalase activity compared to the potato. Again, the null hypotheses that states: the orange will not affect the catalase activity is accepted. References
