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An Investigation Into the Effect of Substrate Concentration On the Rate of Enzyme Activity.

Extracts from this document...

Introduction

AN INVESTIGATION INTO THE EFFECT OF SUBSTRATE CONCENTRATION ON THE RATE OF ENZYME ACTIVITY INTRODUCTION Hydrogen peroxide is a toxic waste product of respiration. It's conversion to water and oxygen is catalysed by the enzyme CATALASE, which is present in most cells. 2H202 2H20 + 02 hydrogen CATALASE ENZYME water oxygen peroxide gas Hypothesis Increasing the substrate concentration will increase the rate at which hydrogen peroxide is broken down to water and oxygen by the catalase enzyme. Null Hypothesis Increasing the substrate concentration will not affect the rate at which hydrogen peroxide is broken down to water and oxygen by the catalase enzyme. Possible Methods There are a number of possible methods for carrying out this investigation. The easiest way to monitor the reaction is to measure the production of oxygen because it is the gaseous waste product: 1) In this method the reaction takes pace in a test tube. The test tube is connected by a thin glass tube to a gas syringe. As the oxygen is given off by the reaction, it travels through the glass tube and into the syringe, this pushes the syringe outwards so there is an increased volume of oxygen in the syringe. As the volume of the syringe increases the amount can be measured on the scale of the syringe: Gas syringe H202 and catalase enzyme The problem with this method is that the reaction starts as soon as the catalase enzyme is added to the hydrogen peroxide. If the bung is not put on top of the test tube very fast some of the waste oxygen might escape and so it would not be measured in the gas syringe. Also, the volume of gas changes with temperature so if the room temperature changes then the results would be affected. The syringe could become more slippery or stiff after each use, this could effect how far the end of the syringe is pushed out. ...read more.

Middle

0.5 250 250 To make sure that the extension was as similar as possible to the main experiment, similar temperatures were used for the extension as were used for the main experiment. First the heat block was set to 20oC. 6 test tubes were taken and 10cm3 of the hydrogen peroxide solution were placed into each test tube. The 6 test tubes were then placed into the heat block and left for 5 minutes to allow them to rise to the required temperature. After the 5 minutes, a disc of filter paper was placed into each of the test tubes, the discs were then pushed to the bottom of the test tube using forceps. As bubbles of oxygen formed on the discs, the discs rose to the surface of the hydrogen peroxide. The time taken for each of the discs to reach the surface of the hydrogen peroxide were recorded onto the results table. The heat block was then set to a temperature of 30oC. 6 test tubes were taken and filled with 10cm3 of the hydrogen peroxide solution. The test tubes were then placed into the heat block and left for 5 minutes so that they could reach the required temperature. After the 5 minutes, a disc of filter paper was placed into each of the test tubes. The discs were then pushed to the bottom of the test tubes using the forceps. The time taken for the discs to rise from the bottom of the test tube to the top was recorded onto the results table. Next the heat block was set to a temperature of 40oC. 6 test tubes were taken and 10cm3 of the hydrogen peroxide solution was placed into each of them. The test tubes were then placed into the heat block for 5 minutes to allow them to rise to the correct temperature. 6 filter paper discs were taken and they were placed into each of the test tubes. ...read more.

Conclusion

This was also done by eye so would have been inaccurate and may have caused variations in timings. Now that the technique has been analysed and perfected the experiment could be repeated. Improvements would be made when measuring out the chemicals. A pipette could be used rather than syringes. If syringes were kept for measuring the chemicals then they could be checked more thoroughly for air bubbles and any found could be expelled by tapping the end of the syringe. The main improvement would be made when making the beads. Each bead could be measured before being used in the experiment. This would mean that any beads that were not the required size could be rejected. Another improvement could be in the timing of the beads travelling from the bottom of the test tube to the surface of the hydrogen peroxide. The beads could be watched more carefully so that the timing became more accurate. Another improvement could be using a larger range of temperature so that the exact optimum temperature could be found. The hydrogen peroxide solutions could also have been left in the heat block for longer so that it was given a chance to rise fully to the correct temperature. More readings could have been made for each temperature to get an even better average for each result. Different methods could have been used so that the results were even more reliable. This experiment could be repeated using different concentrations of substrate (hydrogen peroxide) instead of changing the temperature. The enzyme concentration could also replace the temperature changes. Different sources of catalase enzyme could be used to see if the optimum temperature changed between sources. The pH level could be changed to see what effect it has on the catalase enzyme. A range of different enzymes could be used to see how they vary and at what temperature they reach their peak. Inhibitors could be added to see their effect on the rate of reaction and also using different substrate with the catalase enzyme. 1 ...read more.

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