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Catalase lab. This intent of this lab is to investigate how the factors of different pH levels and how they affect catalyze activity on the decomposition of hydrogen peroxide.

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Sydney Berger Ms. O'Brien IB1 Biology B3 1st November, 2011 IB1 Biology Internal Assessment In terms of biology, an enzyme is a large protein molecule that speeds up or catalyzes chemical reactions found in nature. The intra- and intermolecular bonds that hold these proteins in their secondary and tertiary structures can be disrupted by changes in temperature and pH, and in some cases to the point where their catalytic activity can be destroyed (known as denaturation). All enzymes have an active site, and when a molecule has the correct shape and conditions it binds to one of the reacting molecules. The reacting molecule that binds to the enzyme is known as the substrate. The active site of an enzyme is where a substrate fits to initiate a reaction, or creating an enayme-substate complex as shown below. Catalase is an enzyme found in a variety of tissues of animals and plants that plays a role in the protection of cells. It destroys toxins introduced to cells, and this lab it will decompose the substrate hydrogen peroxide (??2??2) into two harmless products oxygen (??2) and water (,??-2.??). This intent of this lab is to investigate how the factors of different pH levels and how they affect catalyze activity on the decomposition of hydrogen peroxide. This entails measuring the height of the foam resulting from the amount of oxygen and water that the enzyme liberates from the reaction. ...read more.


5. Using a clean stirring rod, gently stir the ??2??2 solution and red potato with a slow, constant pace for one minute. 6. Immediately use a ruler to measure the height of the white foam from the initial height of the solution before the reaction occurred, to the top of the foam after one minute that reaction occurred. ((If you are not adding any pH solution, measure from the 20 mL mark (15mL of ??2??2 solution, 5 mL of red potato). If you are altering the pH of the ??2??2 solution, measure from the 23 mL mark (15mL of ??2??2 solution, 5 mL of red potato, 3 mL of pH solution.)) Record Results. 7. Dump solution in the waster container (NOT down the sink) and CLEAN the test tube (use test tube brushes) 8. To alter the ??2??2 solution, pour 3 mL of the desired pH solution (that is room temperature, ensured by using a thermometer prior) into the graduated cylinder of the initial 15 mL ??2??2 solution and thoroughly stir the mixture. 9. Repeat steps 1-8 using ??2??2 solutions but changing the pH level to 2, 4, 6, 8 and 10. Perform 5 trials for each different level. Raw Data- Qualitative- As the lab was being performed, qualitative observations included the most bubbles formed the quickest around the pH levels of 6 and 8, and the bubbles were very dense and thick. ...read more.


Also I did the best I could to control the temperature of all of the materials and keep them constant, but when I could not record the temperature there could have been slight variations that could alter the result, considering catalase is sensitive to temperature change. As a limitation using a wide range of pH solutions would give a broader prospective of how varied pH levels of a substrate truly affect catalase activity, however the recourses were not present at the time. If I had access to more than 5 different pH levels, the extra data points would establish a stronger support for the quadratic relationship. Anomalies that I had encountered included separation of the solid and liquid of my Red Potato catalase Source, and knowing that if I tried to react and un-mixed catalase source, my results would probably be less effective and have less foam. To minimize these adverse effects, I paid critical attention to my catalase before each trial and was constantly stirring it back to its original condition. All in all, the experimental design did answer my research question and had minimal adverse results due to poor lab techniques. The reliability of my data corresponds with my background information, and provides stable evidence with quantitive and qualitative data to support. Suggestions for Improvement 1) A larger range of pH solutions to alter the H202 solution would establish a stronger relationship. 2) Using an O2 detector could provide a more accurate detection of the oxygen liberated from the reaction. Resource of Picture: http://www.rsc.org/Education/Teachers/Resources/cfb/enzymes.htm 1 Berger ...read more.

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