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# The effect of temperature on catalase activity

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Introduction

The effect of temperature on catalase activity Hypothesis I predict that the breakdown of Hydrogen Peroxide will be quicker when the temperature is increased until it exceeds 40�C, the enzymes optimum temperature is at 35�C. This is because a rise in temperature increases the rate of most chemical reactions and a fall in temperature will slow them down. In many cases a rise in 10�C will double the rate of reaction in a cell. This is particle theory. I am going to investigate the temperature at which reactions occur. I predict an increase in temperature will result in an increase in kinetic energy. Since the speed of particles increases, they should collide more often and therefore the speed of reaction increases. The particles will also have more energy thereby speeding up the reaction even more. It has been suggested that for every 10 degree rise in temperature, the speed of the reaction will double. At low temperatures particles of reacting substances do not have much energy. However, when the substances are heated, the particles take in energy. This causes them to move faster and collide more often. The collisions have more energy, so more of them are successful. Therefore the rate of reaction increases. The more successful the collisions are the faster the reaction. The same can be said for reactions controlled by enzymes, but because enzymes are proteins if the temperature exceeds 50�C the enzyme will be denatured and will no longer work. For this reason few cells can tolerate temperatures higher than approximately 45�C. ...read more.

Middle

7) Add the potato cylinder to the tube and leave for exactly one and half minutes. As time is another control variable. 8) Maintain the temperature of the reactants otherwise temperature of the individual experiments is no longer constant. 9) Measure the height of foam up the tube with a rule. 10) Repeat the procedure for the three other temperatures. Note this is the feature under test, is the uncontrolled or key variable. Results Temperature �C Height of foam in cm initial rate ( gas/ time) cms-1 5�C 2.6 cm 0.03 cms-1 20�C 5.2 cm 0.06 cms-1 35�C 7.0 cm 0.08 cms-1 70�C 0.3 cm 0.003 cms-1 Group Results Temperature Height of foam in cm Average 5�C 1.4cm 1.4cm 1.2cm 1.6cm 1.4cm 1.5cm 2.6cm 1.6cm 20�C 2.1cm 2.3cm 2.1cm 3.0cm 1.9cm 2.5cm 5.2cm 2.7cm 35�C 3.9cm 4.0cm 3.6cm 4.5cm 3.7cm 4.0cm 7.0cm 4.4cm 70�C 0.2cm 0.2cm 0.2cm 0.4cm 0.2cm 2.0cm 0.3cm 0.5cm Analysis My results proved my prediction to be correct. The breakdown of Hydrogen Peroxide accelerates as the temperature increases until the optimum temperature after which it begins to slow down. Temperature influences the rate of enzyme activity. Usually a 10�c rise doubles the rate of enzyme activity. This is only true up to an optimum temperature, however beyond this point (usually 40�c) the 3D shape of the active site becomes distorted and the enzyme becomes inactive. Cooling or even freezing does not destroy enzymes, though it slows down their activity. From studying the graph and our results table we can see the enzymes optimum temperature (35�c). ...read more.

Conclusion

Maintaining at the constant temperature is the most difficult part of the experiment, in order to improve this; an electrical water bath can be use instead of individual beaker. A pH buffer should be used to maintain a consistent pH level in the boiling tubes. This way there was no variation in pH that might have resulted in an increase or decrease in the rate of reaction. However this was not available at the time of the experiment. Laboratory coats were worn during the investigation to prevent chemicals from spoiling clothes. Care was also taken whilst handling the chemicals as hydrogen peroxide is corrosive. Whilst using the cork borer, care was also taken as it may cause cuts on skin. The precision of this experiment, generally, was very limited since insufficient readings were taken. More different temperature such as 45�C, 55�C should be taken in order to produce a more accurate set of results and the graph would then can be used to predict further temperatures. In this investigation each reading should be repeat so that an average rate of reaction for each enzyme concentration could be calculated. This could be improved by repeating the reading more frequently thus reducing the extent of any anomalies further, once averaged. For further work, we are alter the controlled and key variables of varies experiment, such as using different concentration of alcohol, since alcohol can break down lipids that are within the cell surface membrane, which will also should the effect of alcohol on membrane permeability. ?? ?? ?? ?? Jessica Leung 1 ...read more.

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A good account of the investigation but the use of more A level standard biological language would have improved its quality. There is a lot of repetition of relevant theory in places and in the analysis section theory is not related to actual results effectively.

Marked by teacher Adam Roberts 17/09/2013

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