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The effect of hydrogen peroxide on catalase if you change the temperature.

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Introduction

The effect of hydrogen peroxide on catalase if you change the temperature AIM Effect of temperature of the action of the Enzyme Catalase. PLANNING Background Knowledge An enzyme is a biological catalyst, it alter the rate of reaction without being changed itself. Enzymes are proteins; they have a very precise three-dimensional shape, which forms a one specific active site on the enzyme. Each enzyme can only convert one kind of substrate molecule in to one kind of product molecule. These are specific. What affects Enzymes? � Temperature- Enzymes stop working if the temperature rises above 40�C. Increasing the temperature alters the 3D shape and so the enzyme can no longer fit the substrate. � pH- They work best in neutral conditions neither acidic nor alkaline. What affect does catalase have? Catalase is a very fast reacting enzyme, it is found in many living cells, it breaks down hydrogen peroxide to water and oxygen. In fact one molecule of it can deal with six million molecules of hydrogen peroxide in 1 minute. Hydrogen peroxide is toxic so needs to be changed into harmless substances. Catalase Hydrogen peroxide water + oxygen 2H2O2 2H2O + O2 References to practicals referring to enzymes � Biology for You Pg 30 - Experiment 3.1 From looking at this I found out that catalase reacts with hydrogen peroxide to give out water and oxygen. Oxygen bubbles produce froth on the surface of the solution. In my forthcoming experiment I will expect to see froth being produced. � Biology- Nelson Science Pg 25 - Picture 4 From looking at this graph, see below. I have learnt that the affect of temperature does in fact change the rate of reaction. From the graph the reaction reaches 40�C but then denatures and the rate of the reaction decreases. The rate falls rapidly suggesting denaturing. Taking this information into account I would expect the enzyme catalase to show a similar pattern with respect to the temperature. ...read more.

Middle

iii) Substrate Concentration - When there is an excess of enzyme molecules, an increase in the substrate concentration, produces a corresponding increase in the rate of reaction. If there are sufficient substrate molecules to occupy all of the enzymes' active sites, the rate of reaction is unaffected by further increases in substrate concentration as the enzymes are unable to break down the greater quantity of substrate. To control the substrate concentration, identical quantities of the substrate were used for each reading. To ensure that this was measured precisely, 5ml syringes were used to accurately gauge to exact quantities. iv) Inhibition - Inhibitors compete with the substrate for the active sites of the enzyme (competitive inhibitors) or attach themselves to the enzyme, altering the shape of the active site so that the substrate is unable to occupy it and the enzyme cannot function (non-competitive inhibitors). Inhibitors therefore slow the rate of reaction. They should not have affected this investigation, however, as none were added. v) Enzyme cofactors - cofactors are none protein substances which influence the functioning of enzymes. They include activators that are essential for the activation of some enzymes. Coenzymes also influence the functioning of enzymes although are not bonded to the enzyme. Unless enzyme cofactors were present in the potato tissue containing the Catalase, they were not included in this investigation and therefore would not have affected the rate of reaction and the results of this experiment. vi) Enzyme Concentration - Provided there is an excess substrate, an increase in enzyme concentration will lead to a corresponding increase in rate of reaction. Where the substrate is in short supply (i.e. it is limiting) an increase in enzyme concentration has no effect. I varied the enzyme concentration by altering the number of equal sized discs of potato that contain the Catalase, in the reaction. The greater the number of discs, the greater the enzyme concentration. ...read more.

Conclusion

I will add 5cm3 of hydrogen peroxide each time in order to keep the test fair. I will use a measuring cylinder to measure out all these values. I will repeat the test at each value three times and then take an average to make it a fair test and I will also keep the temperature of the room the same throughout the experiment using the thermostatic controls in the laboratory. The temperature will remain at 20�C. These are the measurements I will be using. TEST TUBE Enzyme(POTATO)(Cm3) WATER(Cm3) Substrate (Hydrogen peroxide)(Cm3) TOTAL VOLUME(Cm3) 1 0 5 5 10 2 1 4 5 10 3 2 3 5 10 4 3 2 5 10 5 4 1 5 10 6 5 0 4 10 Results Test Tube Experiment No.1 Experiment No.2 Experiment No.3 Total Average 1 0 0 0 0 0 2 2.3 2.1 2.4 6.8 2.3 3 4.3 4.5 4.4 13.2 4.4 4 6.8 6.5 7.1 20.4 6.8 5 7.4 7.4 7.1 21.9 7.3 6 7.4 7.5 7.2 22.7 7.4 Conclusion In conclusion I can see that my prediction was correct. The higher the enzyme concentration was, the more oxygen was produced. This is because the with higher enzyme concentration, there are more active sites where more successful collisions will take place between the active site of the enzyme and the substrate. The graph shows that as the enzyme concentration was increasing more and more, the rate of catalyse activity was increasing less an less which indicates that it was nearing the optimum rate of catalyse activity. Evaluation My experiment worked well although if I were to do it again I could do certain things differently in order to gain more accurate results. I would repeat the experiment more times as this would give me a more accurate average and I would also uses more different values in order to get a more detailed outlook on how enzyme concentration affects the rate of catalyse activity. I would also use a measuring syringe to measure the amount of oxygen because this is a much more accurate way of doing it. ...read more.

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