Variables
The only factor of the experiment I will change is the different temperatures I will use to compare the rate of enzyme activity. The temperature will range from 10’c to 100’c and the temperature will increase in tens each time. Each sample will be taken in intervals of 30 seconds until no starch is present. Also, the amount of starch and amylase is to be kept the same otherwise the time taken to brake down all of the starch may increase or decrease, resulting in inaccurate results. Any unwanted variation may cause the results to become inaccurate; therefore I will repeat the investigation three times and take an average so the abnormal results will not greatly affect the final results.
Hypothesis
I predict that the enzyme activity will be at its highest where the temperature is closest to body temperature. As enzymes denature if the temperature is too high I believe that around 60˚c the enzyme activity will have decreased sufficiently and will denature completely beyond that. This means that my results should produce an almost-perfect bell curve, where the highest point is at 37˚c. Whilst this occurs I should see the iodine black when starch is present, becoming brown/black as the starch is broken down to finally seeing the iodine brown/orange where there is no starch present. Where the temperature is extreme I predict to see no or vary slow and little change in colour to the iodine solution.
I created the following graph to represent the trend of results I am expecting.
Results
The following table shows the times for the amylase to completely brake down starch to maltose.
To enable me to work out the rate of the enzyme, amylase, I used the simple formula:
Rate=1/Time
The following page shows my actual results for my investigation as a graph.
Conclusion
The majority of my results produced the expected bell curve on my graph. However, I believe due to human error the results were incorrect between temperatures of 60˚c and 80˚c causing this area of my graph not to follow the pattern of my initial prediction. I have also noticed that the highest rate is at a slightly higher temperature than I expected, though this may be due to the large difference in temperature between each sample. As the temperature was increases the molecules were given more energy and move around in the solution quicker increasing the chances of collision, speeding up the brake down of starch. I had found that where the temperature was above 40˚c the enzyme did not work as efficiently, even with the extra energy, as they had become deformed. Where the enzyme does not work so well or does not even work at all the active site if the enzyme had changed. The enzyme had not died as it is not a living organism. With the shape of the active site changed the enzyme is unable to perform the “lock and key” action the enzyme is meant to do in order to catalyse a reaction. The specified enzyme is shaped to “lock” on to the substrate. Where the enzyme contacts the substrate is called the active site. When the enzyme becomes denatured the shape of the active site has changed and the enzyme is no longer as efficient. The enzyme can become so deformed that the protein molecule begins to unravel making the enzyme completely useless.
Evaluation
From the research that I had done and the graph I had produced for my hypothesis, I can see that my results are fairly reliable until 60˚c. I do not believe that my test was fair as the temperature which I took samples from did not increase exactly in intervals of 20˚c as I had intended. Therefore if I was to repeat my investigation I would attempt to have the temperature exact to my method. I also notice while doing this experiment that some sample were taken every 30 seconds whiles others were taken every 40 seconds. To eliminate this problem the stop clock should be watched carefully and the person taking the sample must be ready well before it needs to be taken. I would also, like the temperature, change the intervals of witch they were taken to increase the accuracy of my experiment. Sometimes it was often hard to differentiate between the changes in colour which could have given inaccurate times. Some one else to do this investigation may have their times different due to their opinion in colour change.
