I will take measurements at five different temperatures, as that is the minimum amount of points you should put on a graph. I will do the experiment at 37 degrees as this is body temperature and so it would be a good idea to see how enzymes react at this temperature. I will also do the experiment at 50 degrees as this is at temperature higher than what the enzymes usually work in that are in the body. I will also do the experiment at 60 degrees, as this is an extreme difference between the normal body temperature. On the other hand it would be good to see how enzymes react in cooler temperatures, so I will do the experiment at 22 degrees as this is under body and is also room temperature and so this will be easy to do as the solutions do not need to be heated as they will already be at room temperature. Finally I will do the experiment at 0 degrees, as it is an extreme difference in temperature from the body temperature. The way in which to get this result is not to put it in a water bath, but to put it in ice; this should reduce the solutions to 0 degrees. All the readings that are to be taken whilst doing this experiment should be done three times and then the average result taken from these, as this will increase accuracy in the results.
To make sure that I work safely I must wear safety goggles, which should be worn whenever doing an experiment. I must also be very careful whilst using the water bath as it is quite easy to scold yourself. To make sure the experiment is a fair test then I must have the amalase and starch at the same temperature and I must also add them to the iodine at the same time. I must also put equal amounts of starch solution and amalase solution to the same amount of iodine. When you do the experiment three times at the same temperature this is not to make it a fair test; this is infact as I have said before, to make your results more accurate.
Prediction
I think that when the enzymes are at body temperature then they will work quickly, this is because when the enzymes are in your body then they obviously work, for the absence of even one enzyme in the body can cause illness, for example, people who do not produce the enzyme lactose can’t digest the sugar ‘lactose’ they get cramps and diarrhoea if they consume lactose in dairy products, this is because the sugar builds up in their gut. Therefore the solution should stay brown, as the enzymes break down the starch into glucose and iodine doesn’t react with glucose; it only reacts with starch. But, when the enzymes are mixed with the starch and iodine when they are at higher and lower temperatures than body temperature, then I think they will not work as quickly and therefore, the solution should go black as the starch will react with the iodine as it has not been broken down and then it will take longer for the solution to return to brown (the starch has been broken down) .
Some evidence for this prediction is when you test for the effect of pH on enzymes, you add amalase and starch solutions at various pH levels (2:Acidic, 7:Nuetral, 12:Alkaline) and then you watch whether the reaction turns inky black or if it stays brown. The solutions only stayed brown when the pH level of the starch was at 7, this means that the enzymes only worked at neutral, even if the starch was slightly acidic, then it wouldn’t work, slightly alkaline, and it wouldn’t work. This is because acid and alkali denature most enzymes. This means that the active site of the enzyme would change shape. The active site is what makes the enzyme substrate specific.
If enzymes get denatured by acid and alkali substances, then I think that lower temperatures than body temperature and higher temperatures then body temperature will also denature enzymes (change the active site).
The only pattern that there will be is that as the temperatures get closer to body temperature then the reaction rate will be faster.
Results
Analysing Results
According to some extra reading I have been doing my results do not really tell me what I would expect.
According to ‘Key Science’ by David Applin the enzymes should work quickly at body temperature, but then work a lot slower the cooler or warmer it was that the temperature of the enzymes were in ( what my prediction said ). This is nothing like what my actual results were; my results show that the warmer the temperature that the enzymes are in, the quicker the reaction takes place.
I don’t really know why my results were so far from the right results, but there was bound to be some unreliable results, as the experiment was done over two lessons and the enzymes used in the second lesson were stronger than that of the first. There was nothing I could do about this and so it wasn’t really my fault. The temperatures I did in the first lesson were: 22degrees, 37degrees and 60degrees. The temperatures I did in the second lesson were: 0degrees and 50degrees.
Evaluation
When I did the experiment, I tryed to stay to my plan, but I had to change my plan whilst I was working. The plan was to put 5ml of amalase and starch into 5ml of iodine, but once doing the experiment I realised that a 15ml solution would not fit in a spotting tile, so I decided that it would be much more logical to put 1ml of amalase and starch into 1ml of iodine.
Apart from this small change, I did not alter my plan at all; my plan was good but still not totally ‘perfect’.
My prediction was correct as I based my prediction on the experiment for seeing how enzyme action is affected by pH level, this was correct because once again ‘Key Science’ by David Applin shows the graph for how pH level effects enzyme activity (amalase). If I wanted to write out the prediction again based on the book, it would be:
I think that amalase will work quickly at body temperature and then the reaction will get slower the colder or warmer the temperature is that that the enzymes are in. I think this because the book ‘Key Science’ by David Applin shows what the graph should look like, it shows a graph with the positive coefficient of x², but if I was to draw the graph it would have to have a negative coefficient of - x² because the graph in the book has on its y axis reaction rate and so, the higher up the y axis, the quicker the reaction and the lower down the y axis, the slower the reaction is. Since I am drawing graphs with time upon the y-axis then the graph would be turned completely ‘upside down’ as the higher up my y-axis the slower the reaction and the lower down my y-axis, the quicker the reaction.
I did not write this prediction originally but my prediction was still correct.
Final Conclusion
Overall I think that my experiment was done quite well and I stayed to my plan apart from the amount of enzyme, starch and iodine. The only thing disappointing with the experiment was that the results weren’t correct.
