Catalase Hypothesis Prediction Worksheet Word PDF

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lab report on catalase activity...

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Hypothesis & Prediction Worksheet A Catalase Activity Assay Name: Mansi Mansi Lab Instructor: Neilab Amiri

Section:

S07

Null Hypothesis0 (H ): The changes in pH levels have no effect on the rate of reaction (mL/sec) of catalase enzyme in the beef liver (Bos taurus).

Alternative HypothesisA( H ): The changes in pH levels have an effect on the reaction rate (mL/sec) of catalase enzyme in the beef liver (Bos taurus).

Predict the effect changes in pH will have on the activity of the enzyme, catalase. Be sure to include an in-text citation and record the reference in proper APA format. There is no increase in catalase activity when the pH is below 6.0 but there is slight increase in activity during stages of pH 6.0 to 7.0. one would expect a rapid increase in enzyme activity when cells are subjected to acid pH (McCarthy e.t.a.l,1959). Reference:

McCarthy, B., & Hinshelwood, C. (1959). Variations in Catalase Activity during a Bacterial Growth Cycle. Proceedings of the Royal Society of London. Series B, Biological Sciences, 150(938), 13-23. Retrieved from http://www.jstor.org.ezproxy.kpu.ca:2080/stable/83050

Result: The reaction rate of catalase increased as the pH level increased from 3 to 7 and started decreasing with the increase of pH from 7 to 11 (Figure 1). The activity rate of the enzyme catalase escalated to 1.13 mL/sec from 0.1mL/sec with an increase in pH from 3 to 5 which reached at its peak at pH 7 having its value equal to 1.43 mL/sec. However, the value of reaction rate of the enzyme catalase touched the bottom (0.4 mL/sec) when pH was 11. Table 1: Varying activity rate at different pH levels pH of the Solution 3 5 7 9 11

Reaction Rate of catalase (mL/sec) 0.1 1.13 1.43 1.23 0.4

Figure 1. Graph of different reaction rates(mL/sec) at different pH levels in beef liver (Bos taurus) Discussion: The objective of this experiment was to observe the effect of different pH levels ranging from 3 to 11 on the activity of enzyme catalase in beef liver (Bos taurus). The results of our experiment permit us to reject the null hypothesis because the reaction rate of catalase is

affected with the change in pH (3.0, 5.0, 7.0, 9.0 and 11.0). We provide support for the alternative hypothesis which states that the change in pH will influence the reaction rate (mL/sec) of enzyme catalase. Water was used as a control in this experiment instead of catalase and it was tested for an effect in pH 7 buffer solution. The purpose of this control was to record the volume of displacement which was further used to record the adjusted data of volume in different pH levels. The reaction rate at pH 3 was 0.1mL/sec which increased to 1.13mL/sec at pH 5 and 1.43mL/sec at pH 7. However, at pH 9 the enzyme activity decreased to 1.23mL/sec and further declined to 0.4mL/sec at pH 11. The reason for this trend is because at pH higher or lower than 7 the enzyme become denatured and start losing its structure therefore, the enzyme activity decreases. Catalase was immobilised on the chitosan film that is a natural polymer[ CITATION Şen00 \l 4105 ]. It was determined that optimum temperature for free catalase and immobilised catalase on chitosan film is 25°C and optimal pH is 7.0 [ CITATION Şen00 \l 4105 ]. There was a big difference in maximum values of kinetic parameters between free catalase and immobilised catalase[ CITATION Şen00 \l 4105 ]. Our findings are congruous with these results as optimal pH of catalase was 7.0 in the free catalase and immobilised catalase. These findings suggest that pH 7 affected the reaction rate highly. The tertiary structure of an enzyme is responsible for proper functioning. The correct substrate binds to the active site of enzyme and form enzyme substrate complex but if shape of active site changes it will not bind. pH and temperature can change the shape of the enzyme thus denaturing them and changing their structure. Main sources of error in this lab can be human errors as timing and communication can be crucial. Volume recorded should be done accurately but sometimes reaction takes place rapidly.

Catalase concentration could also be an error as the reaction rate could change, with higher catalase concentration the reaction rate would increase and decrease with lower concentration. To minimize such errors, readings should be done carefully with concentration and timing should be kept in notice. In conclusion, we expected that the optimum pH of catalase in beef liver (Bos taurus) was 7.0 and from the experiment, the result support our prediction that reaction rate increases at pH 7.0 and decreases at other pH levels.

References

Çetinus, Ş. (2000, April 13). Retrieved from https://www.sciencedirect.com/science/article/pii/S0141022999001891#!

Faculty of Science and Horticulture. (2019). Biology 1210: Introduction to Biology 2 (Spring 2019 ed.). Surrey, Canada: Kwantlen Polytechnic University Bookstore. McCarthy, B., & Hinshelwood, C. (1959). Variations in Catalase Activity during a Bacterial Growth Cycle. Proceedings of the Royal Society of London. Series B, Biological Sciences, 150(938), 13-23. Retrieved from http://www.jstor.org.ezproxy.kpu.ca:2080/stable83050 Reece, J. B. (2013). Campbell biology / Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson, Fiona E. Rawle, Dion Glenn Durnford, Christopher D. Moyes, Sandra J. Walde, Kenneth E. Wilson. Don Mills, Ontario: Pearson Canada....