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What Affects The Action Of Catalase Enzyme On The Decomposition Of H2O2?

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Introduction

Sadie Tulley Biology Coursework, Sept 2001 Page 1 What Affects The Action Of Catalase Enzyme On The Decomposition Of H2O2? Planning Catalase is a biological catalyst that breaks down Hydrogen Peroxide (H2O2) into Water (H2O) and Oxygen (O2). Below is the reaction that takes place: - Hydrogen Peroxide � Oxygen + Water H2O2 � O2 + 2H2O Reactions can be speeded up through the use of a Catalyst, this is a substance which changes the rate of a reaction but is not actually used up so they can be re-used; in this case we will use Catalase. Catalase is an enzyme, which is found in living things such as yeast and liver, the enzyme is used in the cells to remove Hydrogen Peroxide which is a waste product made by all cells, H2O2 is very toxic and so breaking it down quickly is very important. How does Catalase work? All enzymes work in the same way, there are two main molecules in the reaction, the enzyme and the substrate, the substrate is the molecule the enzyme acts upon. The enzyme has a small section called the 'active site', which is the exact shape to fit around the substrate molecule; this is called 'the lock and key hypothesis'. ...read more.

Middle

All the chemicals I will use will be kept at room temperature before and during the test, this means that they will all be the same temperature (approx. 21�C). To keep the concentration of Catalase the same throughout the test I will sort through all the yeast beads I make so that the ones I use are all the same size and shape, I will also discard immediately any "floaters" as these beads already contain air and so are useless. Instructions 1. Wearing safety goggles take 5cm� of Sodium Alginate Jelly and 5cm� of Yeast Suspension and mix together in a small beaker. 2. Fill up another small beaker with 50cm� of Calcium Chloride. 3. Use the syringe to suck up the jelly and yeast mixture, slowly drop it into the CaCl2 drop by drop, as the mixture goes in it will form small beads, make about 30 beads. 4. The beads should sink immediately to the bottom of the beaker, any that do not should be removed also any that have "tails" or are not round should be removed to keep the test fair. 5. ...read more.

Conclusion

7 predicted would happen, if I was to re-do the experiment I would test a higher concentration of Hydrogen Peroxide to back up this part of my prediction. If I were to repeat the experiment I would probably drop more yeast beads into each concentration of H2O2 so my average would be more statistically valid. The results I have gained may be slightly erroneous because my reaction speed is not very fast, this means that I could have stopped the stop clock too soon or too late making my results inaccurate, to make up for this I rounded the results up to the nearest half a second. Temperature probably did not affect my experiment because all of the ingredients were kept in the same place at room temperature and all the tests were done on the same day within an hour. I could measure the rate of reaction in a completely different way to gain more accurate results; the method I would use to do this would be to use a conical flask to do the experiment in and then catch the oxygen gas produced in a gas syringe, using this method it is easier to read the results accurately, leaving less room for any imprecision. ...read more.

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