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To find out what a change in concentration of concentration of enzymes does to the length of time it takes to make the substrate into the product. I will use starch as the substrate, and amylase as the enzyme.

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Introduction

Enzyme Experiment Planning Aim To find out what a change in concentration of concentration of enzymes does to the length of time it takes to make the substrate into the product. I will use starch as the substrate, and amylase as the enzyme. To test that the starch has changed into maltose, I will use iodine. Iodine turns black/blue in the presence of starch, and stays orange if not. Therefore I will be testing how long it takes for the iodine to stay orange. Prediction I think that as the concentration gets less, it will take longer for the enzymes to change the starch into maltose. This is because the fewer enzymes there are, the less the starch can come into contact with their active sites and therefore fewer reactions can take place. From the graphs made with 'Enzyme Lab', they show that when the concentration of substrate decreases, the reaction rate increases. I think the opposite would happen if the concentration of enzymes decreases. I predict the best result will happen when the enzyme concentration is the highest. I also predict that the graph at the end will be a straight line of concentration on the x-axis and time on the y-axis. I think that the concentration of enzymes will be directly proportionate to the time taken, because as the enzyme concentration gets lower and lower the time it take swill get longer and longer at the same rate. Apparatus list * Amylase - as the enzyme * Starch - as the substrate * Water - to make the volumes equal * 3 100ml beakers to hold the amylase, starch and water in - this would hold enough of the solutions for the experiments * Iodine - to test whether the starch has turned into maltose * Dimple trays to put the iodine in to test for starch - this was used in my preliminary experiment and was the most effective way of testing for starch * Timer in seconds - to ...read more.

Middle

If there are more enzymes, there is also a greater chance of their active sites colliding into the substrate to form the product. Since the temperature was 40�, the optimum temperature, the enzymes and substrate had the greatest chance of meeting as they had the greatest amount of kinetic energy. Kinetic energy is the amount of energy the particles have to move about. The more enzymes, the more times the substrate will meet and therefore produce the maltose. Any higher than 40� would make the particles have even more energy to collide, however the enzymes would become denatured and therefore not be able to work at all. My results show that this conclusion is correct. For example at the lowest concentration, 10%, it took the longest time for the iodine to stay orange, 660 seconds. As the percentages went up, the time went down. 100% is the best possible amount of enzymes, because there is the maximum amount of enzymes and therefore the reactions would take the minimum amount of time. Evaluation The method I used was suitable to the experiment because it obtained fairly accurate results and I had no problems with the equipment I used. Everything was the right size and the experiment went well without any safety issues. Anomalous results I have two anomalous results. The 1st is at 70% concentration of enzyme. The 3rd time gave me 270 seconds when the other two were 180 and 180. The 270 seconds even surpasses the 60% concentration, which were at 270, 240 and 240 seconds. The second anomalous result is at the 10% concentration. The times were 600, 750 and 630 seconds; 750 being clearly longer than the other two. There are many reasons that I may have had slightly inaccuracies leading to anomalous results. Such as the fact that the amounts I was measuring were very small, and I could have accidentally used too much or to little of the substrate and/or the enzyme. ...read more.

Conclusion

The method I used assumed the readings would be to a great degree of accuracy; however the results I got weren't totally inaccurate because the three different readings of each concentration are all very similar. Because of these small errors, my results will be affected in that the reaction rate could be slightly faster or slower. The amount of iodine in the blobs and the amount of solution may have given misleading times of when the experiment had finished. To improve and make the experiment better I could do more readings closer together, e.g. 95%, 90%, 85% etc. I could also use bigger amount, instead of 5ml of starch I could use 10, and 20 of varying amount of enzyme and water. This would make it easier to measure the amounts. Time was a hard variable to control. And therefore I could do an experiment on a different factor such as pH. To make even more improvements I could make sure the solution is fresh and not already made up. I could use pH paper with all the experiments to make sure they are all at 7. I could find a different method of finding out if they still contain starch, as iodine is a bit unreliable and compare the results with graphs. Reliability The results are quite reliable since I did the experiment 3 times with each concentration. The results are all similar in the times. The times are usually the same, or only vary 30 seconds either way. However I repeated the tests one after another, and therefore the same "error" could have occurred in all three of the tests. To improve I could do another set of repeats but at a different time, to see if they still have the same results. The results I have agree with my original prediction, scientific background and conclusion and therefore are accurate to a degree. Although I cannot say if my results are correct and that if I do the experiment again they will always be those exact results, they show the correct trend and look reasonable. ...read more.

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