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An investigation into the effect of temperature on the activity of the enzyme catalase found in potatoes.

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Introduction

An investigation into the effect of temperature on the activity of the enzyme catalase found in potatoes. Aim: To investigate the effect of temperature on the activity of the enzyme catalase on the digestion of hydrogen peroxide. Prediction and scientific knowledge I predict that as the temperature is increased from 15 oC to 40 oC the activity of the enzyme the time taken for the enzyme to completely digest the hydrogen peroxide will increase. While at temperatures above 40 oC the activity will start to decrease as the temperature denatures the enzyme. Enzymes are biological molecules made of protein. Each enzyme has a specific substrate because the enzyme shape fits the shape of the substrate. The shape of the enzyme is held together by weak forces of attraction in the enzyme molecule. The way in which the enzyme works is called the 'lock and key' mechanism. The diagram below shows the lock and key mechanism. The substrate fits a special part of the enzyme called the active site. The enzyme-substrate complex reacts and the products are released leaving the enzyme ready to be reused. ...read more.

Middle

62 81 80 74.33333 60 39 42 40 40.33333 65 22 20 30 24 70 6 5 4 5 Analysis and conclusions The results of the experiment are shown in the table and presented in the graph. The graph shows the average number of oxygen molecules. The pattern produced is similar to the predicted graph I presented in the planning. From 15 oC to 35 oC the number of oxygen bubbles produced increased. This is because the increasing temperature increased the kinetic energy of the enzyme and hydrogen peroxide particles. This resulted in the particles moving about faster and more collisions happening. Therefore, more enzyme-substrate complexes formed and more chemical reactions took place. In other words the hydrogen peroxide was broken down faster which is why the number of oxygen bubbles produced increased. The graph shows that the optimum temperature was 35 oC. At higher temperature, the enzyme shape was changed so more of the enzyme particles stopped working (the enzymes were being denatured). At the highest temperature of 70 oC only a few enzyme molecules were working which is why so few bubbles of oxygen were made. ...read more.

Conclusion

Counting bubbles was not easy especially at around the optimum temperature and also the sizes of the bubbles change. If it was possible then I would use a gas syringe to collect and measure the oxygen. 3. The other way I could do this experiment is to use a weighing balance. Since the oxygen gas is escaping I could measure the loss in mass of the reacting mixture. Even though I did not have this equipment I was still able to produce reliable results and make a conclusion. I could use the same apparatus to investigate the effect of pH on enzyme activity or enzyme concentration. To change the pH, I could use acid or alkali mixed with the hydrogen peroxide and again count the number of bubbles of oxygen produced. To change enzyme concentration I could use different sized pieces of potato. However, one of the problems with this would be that the surface area would be different. Therefore, it might be better to investigate surface area in stead. I would keep the mass of potato the same but chop it into different numbers of pieces. ...read more.

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