Now dip the glass rod into one of the iodine filled dimples on the dimple tile. Make sure the glass rod is cleaned in the beaker full of water before taking the next sample, to avoid contamination.
When the stop clock passes thirty seconds, dip the glass rod into the solution again and then into another dimple on the dimple tile. Depending on which temperature the water bath is set at, there should be a noticeable change in the colour of the iodine.
Repeat this experiment at thirty second intervals, cleaning the glass rod each time, until the iodine solution does not change colour at all. Record how long it has taken for the iodine solution to no longer show a colour change and then carefully clear away the apparatus.
Repeat this experiment at least once and then do the same for the other temperatures.
When these experiments are carried out, I can predict what will happen to the enzymes at different temperatures from the knowledge I have gained from the following web page;
.
For instance, I know that should the temperature become too hot, the enzymes will become denatured and no longer fit their substrate.
Here is an example of how an enzyme fits its substrate, it is called the “lock and key” hypothesis;
This hypothesis helps me to understand exactly what happens when an enzyme becomes denatured, as I can tell that the substrate would no longer fit into the active site, and therefore would not be able to be broken down. This also helps me in that I know that if any of the experiments I am planning to do at higher temperatures do not work, it will be because the substrate (starch) will not fit inside the enzyme (amylase) to be broken down.
I can also predict that the experiment will not work at extremely low temperatures because the enzymes will not have enough energy to meet their substrate molecules.
I think that the experiment will work best at around room temperature as I have referred to the following worksheet,
BIOTECHNOLOGY 2 HOW ENZYMES WORK.
From all the research I have done, I can predict that overall; my results will follow a trend in that the enzymes will cease to work at very low temperatures, the rate at which they work will gradually increase up until around room temperature, and then decrease until they get up to high temperatures, where they will also cease to work.
In order for my prediction to have any sort of meaning however, the experiments must be carried out accurately and fairly, otherwise I may obtain biased results which do not fit the normal pattern.
After doing this experiment it is clear that the reaction proceeds at different rates at different temperatures, however after drawing two graphs it is also clear that it follows a significant trend.
When looking at “my graph to show the rate of reaction between starch and amylase at different temperatures” I can see that the rate of the reaction increases with the temperature up to a point and then slows down again. This is because at the extremely low temperatures the enzyme does not have enough energy to brake down the starch. As the temperature begins to increase however, so does the rate of reaction, working best at forty degrees. This is because it is around body temperature, which is where the enzyme itself works. The rate of reaction then slows down as the temperature increases, and more of the enzymes become denatured, until they cannot brake down the starch at all and the experiment fails to work.
This proves the lock and key hypothesis as at the high temperatures the enzymes became denatured, and obviously could no longer fit their substrate, causing the reaction to stop completely.
I am pleased that after doing this experiment that my results supported my original prediction, as they followed the same trend that I suspected they would. I also found that at the higher and lower temperatures the reaction did not work at all so once again, my preliminary research was backed up by my results.
I am pleased because the experiment worked well and I got the results I wanted.
Though my results did follow a significant trend there was one clear anomaly in “my graph to show the rate of reaction between starch and amylase at different temperatures.” This could be for a number of reasons, for instance during one of the experiments the temperature may not have been exactly right or I may have made a mistake when measuring the amount of starch or amylase. There are many other reasons why one of my results could have been anomalous, however I know scientifically that the result should have been closer to the trend line and that it must have been through a mistake of my own that it wasn’t.
Although my results give a rough idea of the points where all the enzymes become denatured, where the enzymes do not have enough energy to work and which is the best temperature for this reaction to take place, it is impossible to say exactly where these points are. This is because I have experimented with temperature intervals of mainly ten degrees, and if I wanted to find out the exact temperatures I would need to experiment with perhaps one degree above and below the temperature that I did use.
It is also possible that the enzymes do react at zero degrees, just extremely slowly. This is why I would like to repeat the experiment, however observing for forty minutes as opposed to just twenty.
If I do repeat the experiment I will probably do it more times in order to find a more accurate average and therefore be less likely to come across an anomalous result.
Even though my results aren’t totally reliable I feel that they can support a firm conclusion because they follow the same pattern that I learned about earlier when doing my research.
