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The effect that potato surface area and Hydrogen Peroxide concentration have on the rate of reaction for the enzyme catalase

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Introduction

Aim: My aim in this investigation is to look at the effect that potato surface area and Hydrogen Peroxide concentration have on the rate of reaction for the enzyme catalase. Preliminary Work: Before deciding on this method of testing I did preliminary work to decide which method would be most effective and provide the best results. First I tried using electronic scales to measure the weight of the potato segment and, looking at its weight at the beginning of the experiment and after ten minutes, calculate the weight loss of hydrogen peroxide. This proved ineffective because the scales were too sensitive and minor tremors could give an inaccurate result. The weight of a gas is also very low, so the results were meaningless. I would have to perform a different experiment. Background: The enzyme I will be using for this investigation is catalase. Catalase is a breaker enzyme found in potatoes that breaks down hydrogen peroxide into water and oxygen. It is the fastest working enzyme currently known. Catalase has evolved to work quickly because hydrogen peroxide is a waste product from reactions taking place within the potato cells, which builds up in the cytoplasm of the potato cell. ...read more.

Middle

Criteria Changed Criteria Kept The Same Concentration of H2O2 pH Value Temperature Potato Surface Area Weight of Potato Prediction: My prediction was that as the molarity or the concentration of hydrogen peroxide increases the rate of reaction would also increase proportionally. This was because the higher the concentration the more molecules of hydrogen peroxide there would be compared to the water in the solution. The particle theory states that the more molecules of hydrogen peroxide there are the greater the chance they will collide with the enzyme and be taken into its active site. As more enzymes arrive at the active site, more will be broken down into oxygen (and water) so at the end of ten minutes more oxygen will have accumulated in the measuring cylinder. Should the concentration reach a point at which all the active sites are being used than the reaction will level off and remain constant. I predicted that the higher the concentration of hydrogen peroxide the more oxygen would be collected in the measuring cylinder at the end of the experiment and that the control would not produce any oxygen. Results: Oxygen After 600 Seconds (ml) ...read more.

Conclusion

These results could be indicating that the enzyme active sites are reaching full capacity as I outline in my prediction. In order to test this I could repeat the experiment but use concentrations of 30%, 35%, 40% and 45% as well. To improve the overall reliability of the experiment I could use a gas syringe to collect the oxygen instead of a measuring cylinder, as the gas syringe would be more accurate at measuring the amount of oxygen given off, measuring the amount to 1d.p reliably. Using a computer program to measure the amount of gas in the syringe with more specialised equipment would yield a further increase in accuracy. Analysing the results for this experiment, even taking anomalies into account the reliability of the results is still good since the amount of oxygen collected in all three repeats are quite close, perhaps measuring to 1d.p with a more reliable method would reveal a closer connection. The anomalies could be caused by the rate of reaction stabilising since the active sites on the catalase enzyme may be reaching saturation point and become unable to accept more hydrogen peroxide molecules. As additional work to further my investigation into enzymes I could do similar experiments to calculate the rate of reaction for other enzymes such as amylase and protease and compare them. ...read more.

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