Time of a Reaction and Its Temperature

Time of a Reaction and Its Temperature
Introduction Enzymes exist in our bodies as biological catalysts. They are there to help reactions, both chemically and biologically, happen faster and in a more efficient manner. Enzymes are created in cells but are released to work in their appropriate places in the body. These are called extracellular enzymes and include most of the digestive enzymes that help break down food in our digestive system. Other enzymes do their work inside cells. These are intracellular enzymes. They not only speed up chemical reactions inside cells, but control them too. The investigation we are looking into involves the enzyme Amylase. This exists in our bodies to break up starch molecules into smaller ones such as glucose or sugar molecules. It works in the manner shown below. The substrate will collide randomly with enzyme molecules. The grooves indented on the surface of the enzyme will fit neatly onto the soft side of the substrate, only IF IT IS the correct match. (Enzyme amylase and starch are a good match)
Once joined together, the places which have fit together is now the active site for the reaction to take place. [image] The reaction is as such: heat Amylase + Starch>>>>>>>> Glucose + sugar Molecules The effect of temperature on amylase will change the shape of the active site on the enzyme part. This in turn will effect the rate of the reaction for good or bad. For example, if the temperature is too high, it might deform the shape of the enzyme active site, therefore the pieces will not fit together properly and react in the normal manner. This happens too when the temperature is too cool. The enzyme will not be flexible or soft enough to be able to fit together into the shape of the substrate efficiently without gaps, so therefore thee reaction becomes smaller and limited at only several places rather then the whole active site. The effect of temperature on Amylase ? Starch reaction Preliminary tests Before any investigation could begin, the proportions of Amylase and Starch had to be fixed. The desired time for a complete reaction would be around 2 -3 minutes (too fast, and we can?t control the experiment; too slow, and it would take too long, reducing the amount of information we could get), so we needed to adjust the amylase ? starch ratio in order to get this reaction time. To do this, we could only use a trial and error method, experimenting individually on each ratio. (e.g. 10:10, 9:10, 8:10 etc) and taking the times of each reaction. The result we got was ideal. 10 ml of Starch would be broken down in around 2 minutes by 3 ml of Amylase. Therefore, for each of the preceding tests, we would use this ratio as it proved a be a good basis for experimenting upon. We also needed to assess the different controls, input variables and output variables of the experiment. ================ Input -? Control Output Temperature Size of tube Same volumes Same concentration Starch Time taken (therefore Rate) Method == Apparatus needed: ? 9 x Boiling tubes ? Thermometer ? Stopwatch ? 2 x Syringe ? Water Bath ? Iodine ? Spotting dishes 1. Place 10 ml of 1% Starch solution into a boiling tube. 2. Change the temperature of the tube and it?s contents to desired temperature (using water bath) 3. Add 3 ml of Amylase using a separate syringe into the tube. 4. Start timing. 5. Test the solution after every 20 seconds using iodine in the spotting dishes until colour is pale yellow. 6. Record this final time and tabulate Tabulating the results. The results given are in time form. To work out the rate of the reaction (ml/s), we need to divide 10 (the volume of starch) by the time taken for that amount to be broken down in the given temperature. Method -?- [image] [image] Prediction == I predict that the starch will broken down quicker as the temperature that it works in is raised. Though, as the temperature gets too high, the rate will ultimately fall and the reaction would not be very efficient. The explanation for this theory is that, the enzyme amylase works at it?s optimum efficiency at around 40-50 C. Below this temperature, and the enzyme won?t have the right environment or the right amount of heat energy to collide and react with starch molecules; therefore not able to perform at it?s optimum efficiency. Above this ideal temperature will ultimately cause the enzymes to fail, as the temperature is way too high and could destroy them. This will mean there is a less concentrated solution of amylase within the starch solution, lessening the chance of collisions and reactions, therefore also lessening the chance of a productive reaction. [image] ? Water baths are hot and can scald skin ? Do not run around with test tubes or hot water ? Do not use pipettes as squirting instruments ? Wear safety goggles ? Be careful as floor may become slippery. Obtaining Evidence -???????- Tabulated results -??????? Temperature -???? ? First Timing (sec) Second Timing (sec) Average Time (sec) Average Rate (10/average time) 17 (room) 120 120 120 0.083 20 100 103 101.5 0.099 30 88 93 90.5 0.11 40 57 66 61.5 0.16 45 - 54 54 0.19 50 45 43 44 0.23 55 - 35 35 0.29 60 60 75 72.5 0.14 70 65 92 78.5 0.13 (The first timing did not include temperature points at 45 or 55 C, as we were only experimenting at 10 C intervals. However, in the second timing, we found it impeccable that these times were needed to give a more accurate and precise indication of the changes of rate over the 45-55 C range.) The results that were taken from the experiment were tested twice to lessen the chance of errors. The results overall were very accurate. We had tested the room temperature on the same day and within a space of 1 hour (the room temperature couldn?t have changed within that short period). The rest of the results were tested with the temperature remaining consistent throughout. (Using a beaker of cold water and a beaker of hot water, we managed to steady any rise or drop in the temperature of the water inside the beaker containing the test tube of starch and amylase solution.) Finally, the timing equipment was very accurate. We used stopwatches to time the reaction and tested the solution frequently (every 20 seconds) using the iodine in the spotting dishes. This meant that our results were accurate to within 20 seconds of the precise reaction time. Analysis Conclusion The graph below shows the rate of the starch ? amylase reaction as the temperature is increased. There is a clear positive correlation as the temperature is raised to around 55 C, meaning that the rate of reaction will become faster and more efficient as the temperature is risen. However, after the 55 C mark, the rate of the reaction drops harshly, returning to a very slow and less efficient manner. This supports the prediction very well, as it defines the following: ? The reaction will peak at around 55 C. ? The environment from which the enzyme amylase works in is somewhere between 50 to 55 C [image] The graph also shows, though in a more discrete way, that the time taken for the reaction to perform will decrease as the temperature is raised. It also means that the time will increase as the temperature is raised to above 60 C.

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