d) Start the stopwatch, Record the result.
4) After every minute, remove 1 drop of the mixed solution and add it to the spotting tile. Read what happens.
5) Record how long it takes for the digestion to be completed.
6) Repeat for one of the other temperatures.
Prediction:
I predict that the higher the temperature the faster the rate of reaction, I think this because of collision theory, which I have explained in my conclusion. I also think that the reaction time will increase as the enzyme denatures.
Results:
At low temperatures enzymes work slower, rises of 10°c will usually double the rate of reaction this is explained by collision theory. The collision theory says that when particles of substances collide with one another there is a reaction. The more collisions, the faster the reaction or the more energy the particles have the faster the reaction. Therefore the higher the temperature the more energy the particles have and the faster the rate of reaction. However enzymes work best at body temperature (37°c) and above 50°c the enzymes change shape, they denature. An enzyme has an ‘active site’ which combines briefly with a substance and changes it – splitting it apart, or linking two pieces together. The shape of the active site fits only one type of molecule, like a lock and key, so it can only control one type of chemical reaction, once the ‘key’ denatures it no longer fits the lock. The results and chart clearly show this, at lower temperatures it took longer for the starch to be digested, at 40°c it took the shortest time to dissolve, after this it started to take a longer time.
Within the results there was very little anomalous data, this seems to be a good set of results, with only a few deviations within them. The results can be plotted onto a graph and show a strong correlation which we expected, the time taken goes up until the enzyme begins to denature and then down as it denatures. If I was to do this experiment again I could do the following to make it better:
- Use different concentration of amylase and starch solution for a wider set of results as this can sometimes affect rates of reaction. Using different amounts of starch solution with the same amounts of amylase at body temperature could simulate how your body digests different amounts of starch i.e. small and large meals.
- Investigate PH levels; acidic or alkaline conditions can alter the shape of enzymes affecting the rate at which they work. From this we could find out which enzymes work well at different PH’s and which enzymes denature at specific PH’s. Suggested PH levels could be 3.7 and 12 for an appropriate range of results.
- Take more care to ensure a fair test. The experiment could have been unfair because of inaccurate measurements and mixture of the solution prematurely or accidentally. The reaction could have been accurately measured, as the colour of the solution did not always change much.