Mechanical digestion, for example the tounge, is used to break the large food particles down so that they are easier to swallow. Once the food has be taken down into the stomach, some more Mechanical digestion takes place but this is helped by Chemical Digestion. Enzymes are there to help break the molecules down. They are Catalysts, which is a chemical that is added to speed up reactions, but remain unchanged by the process. Every Enzyme has a purpose and a special reaction that is involved in the process.
Enzmes control chemical reactions inside all living things. Each of the main food groups have an enzyme that breaks it down.
Enzymes have 5 properties that are always the same:
* They are always proteins
* They are specific in their action
* They are destroyed by a rise in temperature
* They are sensitive to pH
* They can be used over and over again
Working best at a neutral pH value and at the bodies temperature, a rise above 50 degrees celsius changes the shape of an enzyme and they can no longer work.
In my experiment Amylase is the enzyme, which is made in the salivary gland and released in the mouth. The starch is the food which the amylase will act on, this is called the substrate. The product that will be formed is glucose. I am looking to see how long it takes for the starch to be digested by the amylase to make glucose.
I will use Iodine to test to see if starch is present.
When added to the solution, if it turns black/blue-then starch is present, if it is orange-then there is no starch.
My prediction is that the enzymes will work fastest at body temperature, (37 degrees celsius), so therefore the starch will turn into glucose the quickest at this point. I do not think that there will be any reaction after the temperature reaches 50 degrees celcius.
* Dimple tray
* Test Tube
* Test tube rack
1. Set up the experiment as shown in the diagram.
2. Then test to see what the room temperature is.
3. Add 25ml of amylase to 25ml of starch and place in an empty clean test tube which i placed inside an empty beaker.
4. I then briefly stirred the mixture and placed 2 drops of the solution into 1 dimple, and added 1 drop of iodine.
5. After a minute, which I timed using a stopwatch, I added another 2 drops of the solution and 1 drop of the iodine into another dimple. I continued this process until the solution turned orange.
6. I then changed the temperature of the solution by adding heated water in the beaker to heat the mixture. I repeated the entire experiment at many different temperatures.
I have found out that temperature affects the speed at which amylase digests starch into glucose. At freezing point (0 degrees celsius), after 40 mins there was absoloutly no change and this was the same for boiling point (100 degrees celcius). The temperature at which glucose should normally change into glucose the quickest is body temperature (37 degrees celcius), but it average at the fastest time at 22 degrees celsius, room temperature.
My prediction for this experiment was partly correct. I predicted that there would be no reaction at 0 degrees and 100 degrees celsius and I was correct. I was wrong though, by predicting that it would react quickest at body temperature, it was quickest at room temperature. I think that this was because the amylase was artificially created at room temperature.
I think the experiment was overall a sucess. I recieved the results that I needed although they were not what I expected.
There were a few problems which I encountered during the experiment. On of which was that the amylase was artificially made at room temperature and therefore room temperature was its most comfortable state. The dimple trays were also a problem as they were made of plastic. The plastic can sometimes contaminate the solutions whereas porcelain or china doesn’t do as easily. The final problem was that the experiment was continued at different time periods during the day. This meant that the temperature in the room would have been different during periods of the experiment. If the experiment was done again but this time taking all the points made above into consideration, the experiment would finish with a more accurate set of results.
I made sure that the testing was made fair by using the same amount of mixture for each dimple and by keeping the water level around the test tube at the same level. The time between each new addition of solution to a dimple was kept the same, 1 minute intervals.