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Introduction

Investigating Enzymes Aim: - To investigate the effect of temperature on enzyme (amylase) activity. Introduction & Background Information As mentioned above, the aim of this experiment is to determine whether temperature has an effect on enzyme activity or not. To test this starch will be hydrolysed in to maltose with the enzyme Amylase. Fearons reagent will then be added to determine the colour and thus the amount of maltose present. This reagent will indicate the relative amounts of maltose produced at each temperature by colour comparison. The colour intensity's will then be examined by a calorimeter to provide us with the amount of absorbance. Starch Maltose Add Fearons Agent (Turns Red) Intensity examined by a Calorimeter The following shows how enzymes work : - Hypothesis: - Enzymes work best at an optimum temperature, which is 37.5oc in the human body. An increase in temperature supplies more kinetic energy to the molecules. The numbers of collisions between enzyme and substrate will thus increase so the rate of reaction will increase too. Above the optimum temperature, and the enzymes are denatured. Bonds holding the structure together will be broken and the active site loses its shape and will no longer work. This hypothesis will now be tested in this experiment. Safety precautions Safety goggles and a lab coat would be worn at all times. ...read more.

Middle

12. Using water as a reference and a 430 filter use the colorimeter to make a quantitative colour comparison of each tube (Note: initial reading should be 0 before the sample is placed in the colorimeter). Read and note down the absorbance. (The darker the red colour that has developed the higher concentration of maltose in the solution and the greater the absorbance). Results Temperature (oC) Colorimeter Reading (Arbitary Unit) 0 (ice) 0.14 21 (room temperature) 0.28 30 0.36 40 0.36 50 0.32 60 0.05 70 0.05 Conclusion The results obtained were plotted on a graph, which can be seen on the enclosed graph. From the graph we can conclude that our hypothesis was correct. In ice the absorbance was only 0.14 units, which means that the rate of reaction was very slow in ice as the enzyme molecules had very little kinetic energy thus there weren't many collisions between the enzyme and the substrate, in this case between starch and amylase. As the temperature increased to room temperature 21oc, the absorbance increased to 0.28, indicating an increase in the rate of reaction. The same occurred at 30oc, an increase in temperature meant more kinetic energy, thus a higher rate of reaction, hence a high absorbance value (arbitary unit) ...read more.

Conclusion

To overcome this it would have been useful to have several people conducting the experiment together. A digital stopwatch could have been used, as oppose to clock stopwatch, which wasn't very accurate. Additionally, the pipettes caused an error in another way. More accurate results could have been obtained by cleaning the pipette between each reading, or using a new pipette each time solutions were measured out, but this could not practically happen. There was always some solution left over in the pipette from the previous measuring out, thus the measuring out was inaccurate. Furthermore the initial reading on the calorimeter was placed on 0, however this might not always have been the case, thus the final reading could have been effected, to overcome this we could have used a colorimeter with had a digital display. Another cause of an error may be due to the fact that the cuvettes may have been dirty/have finger markings on them as they were handled improperly. Some of the cuvettes were also old thus the light transmitted through may have been obstructed further due to the undesired particles they may have been situated on the cuvette. To overcome this we could have used a spectrophotometer. In conclusion, the accuracy of the results was encouraging enough to make a rational conclusion. If the experiment had been carried out under more strict conditions and with more sophisticated instruments, the conclusion would not have been that different. ...read more.

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