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'Investigating how temperature affects the rate action of the amylase enzyme on starch.'

Extracts from this document...

Introduction

Aim: 'Investigating how temperature affects the rate action of the amylase enzyme on starch.' Background Reading Before conduction of both preliminary and the official investigations, I did research on enzymes, their structures and properties both during school and at home dependently using the internet, varies software and books (http://www.bbc.co.uk/revision / Encarta encyclopaedia / School Biology book). This Investigation should hopefully reinforce my understanding of enzymes and particularly the Amylase Enzyme. I have decided to express the knowledge not in this section but throughout this essay in major areas such as the prediction. Hypothesis: I hypothesise; using my scientific knowledge of enzymes from the essential background reading that increasing the temperature will increase the rate of reaction between the enzyme and the substrate accordingly. However, I am aware that the temperature can only be increased or decreased to a certain point before the reaction corrupts as the enzyme will cease to function. I believe that this will occur at above 45�C i.e. optimum temperature. Prediction: (Theory part of this applies to both the Preliminary and Official Experiment) The focal factor which has been assigned to this investigation is temperature. This Investigation will look at how the temperature affects the rate at which a bacterial amylase enzyme works upon a starch solution. Enzymes are a chain of amino acid polymers and are produced in living cells. They often act as biological catalysts and so catalyse (speed up) a reaction (a catalyst is a chemical substance which speeds up a reaction but does not get used up during it). For example, if starch is mixed with water it will break down very slowly into maltose, taking several years, however, in your saliva there is an enzyme called amylase which can break down starch to glucose in minutes or seconds. So as can be seen, water alone can react with the starch and digest it. In fact the majority of chemical reactions in the body require water. ...read more.

Middle

The Optimum Temperature is the temperature where the amylase functions most rapidly. My Prediction of 45�C for the optimum temperature was due to my knowledge of enzyme and particularly the amylase enzyme. In school and dependably elsewhere I learned that most enzyme function between 30-50�C and denature at about 60-70�C. Though I did not realise that a BACTERIAL amylase enzyme acts differently to the amylase enzyme present in the human body. And so I wasn't aware that it would have a different optimum temperature. Beyond the temperature of 75�C I did not achieve correct results of which I gave the possible reason in the evaluation. At a temperature of 80�C - 90�C my results show a time of 0s, simply meaning that the enzyme must be denatured (ceased to function) (the brown iodine turns blue/black at the start of testing and does not turn the iodine brown). I do know that this is not correct as an enzyme apparently does not denature that fast i.e. 5�C above the optimum temperature. An enzyme goes through a series of changing before it is completely denatured. The structure of its active site jostles and reforms and gradually reaches a point where its active site has changed so much that the 'key and lock theory' does not apply i.e. the substrate 'key' no longer fits into the structure of the active site 'lock'. I have made a graph showing the rate of reaction in the experiment (this is only done for the correct temperatures between 45�C-75�C. The remaining temperatures between 80�C-90�C are incorrect and so I have not included them in. The rate of reaction graph is simply done as a 1/Time graph. 1/Time Results: (Answers taken to four decimal places) 1/Time Rate Results 45 0.0019 50 0.0029 55 0.0034 60 0.0038 65 0.0050 70 0.0059 75 0.0010 Conclusion: I stated in my prediction the following: "Increasing the temperature will increase the rate of reaction between the enzyme and the substrate accordingly. ...read more.

Conclusion

The preliminary results are very faulty as they show that the enzyme is denatured straight after the optimum temperature-only a temperature of 80�C (5�C up, and so is very unlikely). Successfully my conclusion does agree with my prediction and theoretical prediction (can be found in the preliminary section). Evaluating: On the whole, I feel that my official investigation worked out well. My method gave results that were reliable and so could always be counted on to be correct this is because I achieved accurate results by choosing particular apparatus such as the essential water bath. I choose to use the water bath because of its accuracy and that it rules out the possibility of human error. The mistakes which I learned from my preliminary experiment led my to me to make the decision that I must improve my technique by using a very accurate piece of apparatus of which I think I have made an intelligent choice. I am sure that my experiment would not have succeeded if I was to repeat the experiment simply using beakers of water and then 'trying' to maintain that constant temperature. Most things in my investigation turned out the way I predicted. Also nothing dangerous or disastrous occurred because I carried out my investigation according to my safety procedures. All of my results seemed to fit with the main pattern as the comparisons of the graphs show. The graph has a similar shape and all the points fit well. I also felt that I had enough correct results to show a conclusion as the results match with my prediction and my background reading. ==> This successful experiment was due to recognising the mistakes in the preliminary experiment, such as the way the method was conducted, the use of some inappropriate apparatus and lack of concentration. I changed all these, and successfully obtained accurate results of which I am pleased about. [Note: can I please be awarded a mark out of 8-8-8-6 i.e. planning-obtaining evidence-analysis and conclusion-evaluation] Thanks :) ?? ?? ?? ?? Maytham Aomran Page ___ Practical Investigation 1 19/11/2001 Amylase Enzyme Investigating Enzymes ...read more.

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