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See the effects of amylase on starch at different temperatures and to find at what temperature amylase will work best at breaking down starch.

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Introduction

Biology coursework: enzymes Planning Aim: To see the effects of amylase on starch at different temperatures and to find at what temperature amylase will work best at breaking down starch. I will change the temperature to find this out. Prediction: As the temperature increases, the rate of reaction will increase, because the particles will collide more and speed up the reaction, but if the temperature goes too high then the enzyme will denature. I also predict that the enzymes will not work above 45 �C, they will work best at 37 �C (body temperature). Scientific knowledge: Enzymes are proteins, they break down bigger molecules into smaller ones. They control the chemical reactions that happen in our bodies. They are biological catalysts (A catalyst is a substance which speeds up a reaction without getting used up). There are two types of enzymes, intracellular, which control reactions inside our cells and extra cellular, which control reactions that occur outside our cells. The right temperature is needed for enzymes to work at their best. A reaction will only happen when particles collide with each other (In this case amylase and starch). Particles need energy to collide and react with each other, the more energy they have, and the faster the particles will move and react. Heat is needed to make the particles move, if the temperature is too low the enzyme will show low activity, although if the temperature is too high this will damage the enzyme and denature them, this will deform the active site so it looses its shape and cannot react with its substrate. Enzymes have active sites that help it to recognize its substrate (in this case Amylase is the enzyme and starch is the substrate). Each enzyme has its specific substrate and that can only fit onto a certain enzyme active site. This is well known as the lock and key theory, because, just like a key only fits into a certain lock a certain substrate only fits into a specific active site. ...read more.

Middle

Put two drops of iodine into each well in the spotting tile. Use the same concentration of amylase and starch for each experiment, for example if you use 1 mole concentration in the first experiment, the same must be used for the second and third experiment. The same PH level of starch, amylase and iodine to be used. To keep the change of temperature constant for each experiment, for example each ten degrees, and starting from twenty degrees each time and ending at sixty degrees. I will also place 1 drop of the mixture into iodine every fifteen seconds, and I will keep the pipette away from the iodine in order not to contaminate the mixture each time I put 1 drop of the mixture into the iodine Obtaining evidence Actual results table Temp (�C) Trial 1 (s) Trial 2 (s) Trial 3 (s) Average (s) Rate of reaction (1/t-3) 20�C 949 926 936 937 1.06-3 (0.00106) 30�C 812 777 821 803 1.24-3 (0.00124) 40�C 932 901 957 930 1.07-3 (0.00107) 50�C 1203 1273 1241 1239 0.87-3 (0.000807) 60�C DENATURED 0.00 The changes I have made to planned method: The amylase works too slow at lower temperatures such as 10�C degrees Celsius and denatures at 70 and 80 �C degrees Celsius, so I will use values between 20- 60 �C in my experiment, which I will use for real results in my investigation, I will repeat this next experiment two times. I will also use five spotting tiles, because I ran out of spotting tiles on the preliminary experiment and had to put iodine in another spotting tile while putting the mixture of amylase and starch into the one spotting tile I had prepared. Analysis Analysis of graph 1: Temperature of enzymes and how long they took to react My graph shows that the enzymes broke down the starch the fastest at 30�C, it also shows that at 60�C the amylase denatured, this is when the active site becomes damaged and can no longer break down the starch, if this happens to an enzyme it is an irreversible reaction, it can never react again. ...read more.

Conclusion

My results did not fit a pattern, because at 30�C it was not decreasing rate of reaction, 30�C was the only one, which increased the rate of reaction. The experiment worked well but could be improved. I could improve the experiment by doing testing rate of reaction for every 5�C, I could get more results by doing this and analyse the pattern more accurately. Also to improve what I found the optimum temperature to be, I could do the experiment for each degree between 30�C and 40�C. I could also use 1/2ml of iodine in each well to be more accurate, rather than just 2 drops, because this is inaccurate, each drop could be a different value, for example one drop could be 1 ml and another could be 2ml. There was also another problem with the iodine, it was difficult to know when the amylase had turned colourless, there were many different colours and this made the experiment slightly difficult, this could be improved by using a colorimeter, this would give me more reliable results. Another problem that arose was when heating the amylase and starch I did not measure the time that they were exposed to the heat accurately enough, this would therefore mean that if the two substances were exposed to the heat for a longer period of time then they would work better because they would have more energy, or at the higher temperatures, 40�C to 60�C more of the enzymes may have denatured if they were left for a longer period of time. To improve this I could put the substances in a water bath and use a stopwatch, so that I can heat them for an equal time. My results are reliable because I kept the values of everything constant. The tests I carried out were enough to show the full shape of the graph, so I am sure my conclusion is correct. Further work can be done. I could test the amylase and starch at different concentrations and PH levels, to see how these variables affect enzymes. I could do the experiment on other enzymes. ...read more.

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