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To investigate how the change in temperature affects the performance of the enzyme catalase in the breakdown of hydrogen peroxide (H2O2) into water and oxygen.

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Introduction

Biology Coursework Enzymes investigation Aim: To investigate how the change in temperature affects the performance of the enzyme catalase in the breakdown of hydrogen peroxide (H2O2) into water and oxygen. Enzymes are a biological catalysts working in living organisms; they are large complex proteins and highly specific, each chemical reaction requires its own enzyme to help speed up the reaction without taking part in it. This is achieved when the substrate is 'trapped' by the enzymes active site, specifically designed for the particular substrate. Once the two particles are engaged the enzyme will make or break a bond depending on what is required for the certain situation. The substrate will then leave the active site in its new form and the enzyme moves on, this process is otherwise know as lock and key and is demonstrated in the diagram below; Enzymes can be used over and over again but are greatly affected by temperature. If the temperature exceeds its optimum the active site will become denatured and rate of reaction will drop dramatically. The enzyme is then permanently destroyed. Enzymes are also sensitive to pH, different enzymes have different pH optimums which are determined by their surroundings e.g. ...read more.

Middle

are using the optimum 7, to speed up the rate of reaction Concentration - There was only one concentration of H2O2 available Volume - We decided to use 10 discs of potato but this wasn't a sufficient amount of catalase to produce a considerable amount of O2 so in the final experiment we will use 20 discs. In this experiment we used 10ml� of H2O2 but again the reaction was too slow so we will use 20ml� in the final experiment. Range of temperatures - we will be widening the range from 20 - 70�C with ten degree intervals. However if a particular temperature takes more than 15 minutes to reach the 10ml mark we will discard it and it will be anomalous. Once I have found an optimum temperature I will do two more tests 5�C either side to determine a more accurate optimum. Prediction: I predict that as the temperature rises it will take less and less time to produce 10ml of O2. This is because as the heat energy rises in the particles it enables each particle to move around quicker and collide with other particles more frequently with more force, this is called collision theory. ...read more.

Conclusion

As we can see the error bar is quite large so for the quality of these results I can expect to find the curves are not quite as accurate as I would have hoped. To improve the experiment I need to make the error bar smaller, this can be done in numerous ways, from doing the full experiment once I am more prepared for things like the bung getting stuck, so by putting grease on it, it would fit better and prevent leaks. If I shake the test-tube whist in the water bath it would increase mixing of hydrogen peroxide and catalase. These small adjustments as well as more repeated results would hopefully reduce the risk of error. The best-fit line of the graph supported my prediction well so I was able to draw up a good conclusion and could explain where perhaps the results were not entirely as expected. To extend the experiment I could find the exact optimum by doing the test at every increment between 35 and 45�C. Or I could investigate catalase in another substance such as blood or liver or chose a new factor to investigate all together such as pH. ...read more.

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