The main objective of this experiment was to look at the effect of temperature on the rate at which the enzyme catalase found in yeast broke down Hydrogen Peroxide (H2O2) releasing water (H2O) and oxygen (O2) molecules. The experiment was set to measure the activity of yeast catalase using the amount of oxygen produced as a result of the breakdown of H2O2. Similar setups were put up at different temperatures of 50C, 150C, 250C, 350C, and 450C and the enzyme activity at these temperatures compared to determine if there was an effect of a change in temperature on the enzyme activity. There were four groups of students carrying out independent experiments on the same topic with each group experimenting twice with two different samples to increase the credibility of the results.
As seen from the results, the experiment yielded different results i.e. different concentrations of oxygen were measured, at different temperatures for the experiments carried out by the various groups. Table 1 below shows the various results obtained by the groups that experimented with each group experimenting with four different temperatures and their results recorded.
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For group SumiLeko, the experiments started at 150C and was repeated three more times with increments of 100C each time. At 150C, the percentage of O2 gas measured was 0.4987 and this percentage increased to 1.171 at 250C. On increasing the temperature to 350C, the percentage dropped to 0,6264 and further dropped o 0.051366 at 450C. A repeat of the experiment using the second sample displayed an increasing percentage of O2 gas from 0.5082 to 0.7725 and then to 1.419 before dropping to 0.025926 at the temperatures 150, 250, 350 and 450C respectively. The increasing percentage of O2 gas indicated an increase in the activity of the enzyme catalase in breaking down H2O2. Therefore, the first sample showed increased activity as the temperature rose to 250C before starting to drop at temperatures 350 and 450C. The second sample showed increased activity up to 350C before significantly dropping when the temperature rose to 450C. This difference in oxygen concentrations indicated that there was a change in the activity of the enzyme with a change in temperature.
For group Aleca, the temperatures used were 50, 150, 250 and 450C. Just like for Sumileko, the two samples showed a slightly different pattern in the results with the percentage of O2 gas recorded in sample 1 increasing from -0.02775 at 50C to 0.8610 at 150C before dropping slightly to 0.7381 then dropping further to 0.035148 at 450C. The second sample had increasing activity from 50 straight up to 250c after which it dropped to near similar levels as sample 1 at 450C. This ascending activity is seen again in group Juzzi where the percentages of O2 detected gradually increased from 50 through 150 and peaked at 250 before dropping significantly at 450C.
This upward trend where the levels of oxygen detected rose steadily as the temperature increased up to a certain temperature then dropped significantly could be interpreted as a temperature-dependent effect of the level of enzyme activity. Similar patterns of increase in O2 concentrations as temperature rose then dropping after the temperatures rose past a particular point can be witnessed also in the experiments by the other groups. The activity of the enzyme was nearly negligible at 50C in all the experiments before slowly rising with the increase in temperature and peaking at 250C for some of the experiments and at 350C for other experiments, then dropping significantly as temperatures reached 450C in all the experiments. It is visible that the enzyme activity was negligible at the extreme temperatures of 50C and 450C and performing better at either 250 or 350C meaning there could be an optimum temperature at which the enzyme functioned best.
A total of ten experiments were done by the five groups at different temperatures all displaying the same pattern of increase in activity with a corresponding increase in temperature up to a particular temperature after which enzyme activity dropped significantly. It can, therefore, be concluded that an increase in temperature led to an increase in the activity of the enzyme catalase up to a particular optimum temperature before dropping again with temperature increases past the optimum temperature. An average of the results per group resulted in more experiments peaking at 250C than at 350C thus 250C could be taken as the optimum temperature for the activity of enzyme catalase as per the experiments conducted. There were more experiments conducted at 250C than at 350C thus more data at 250C for one to work with.
A number of limitations could have affected the results of the experiment including; the use of an old gas sensor which would mean the measurements of O2 levels may not have been as precise as desired; the positioning of the sensor at the top of the Nalgene Vernier bottle which would mean there was some distance between the sensor and the location of the sensor at the bottom of the bottle. Another limitation could be user-related where the bottles may not have been cleaned properly before being used again for the next experiments thus contamination of the data. These limitations were however considered not significant enough to affect the credibility of the results from the experiments.
