Size of photographic film (using a ruler).
Prediction: I think that the trypsin (pH9) will work best around 35 °C.
Explanation of prediction: Trypsin is an enzyme that breaks down proteins into amino acids. It is made in the gall bladder and works in the small intestine. The photographic film has a black protean gelatine coating and trypsin breaks down proteins so therefore will break down the coating and the film will just become a clear strip of plastic. Trypsin usually works at pH8 or pH9 (alkali conditions) and at human body temperature, which is normally 37-38°C. Considering that those conditions are its normal conditions, I think that they will be its best conditions. Basically I think that, if the temperature is too low then, due to insufficient amounts of energy this will slow down the trypsin’s speed of breaking down the gelatine and if the temperature is too high then it will start to kill off the enzyme which will also slow it down, so it needs to be somewhere in between.
Preliminary test: I did this experiment previously to test whether the range of temperatures or the equipment needed to be changed. Here are the results of the preliminary testing:
Temperature (°C). Time (secs).
- 1173
- 588
- 540
50 1188
Preliminary conclusion:
These results are very spread out and therefore show that more temperature values will be required in the actual test. Also the results could contain anomalies so I will need to repeat each temperature 3 times to get an average and base my results on the averages.
Method:
Equipment:
- 75ml Trypsin at pH9.
- 15 strips of equally sized photographic film.
- 5 test tubes.
-
5 water baths at 30°C/35°C/40°C/50°C and 60°C.
- 5 stopwatches (1 for each water bath) to measure the time.
- A measuring cylinder to measure the 5ml for each tube accurately.
- A thermometer to accurately check if the temperature of each water bath is correct.
Plan: Pour 5ml (for reasons of fairness)of Trypsin (pH9) into each test tube and then place each tube into different water baths that have been allowed a few minutes to warm up to their specific temperatures. Leave the tubes for about 5 minutes so that they have a chance to warm up to their temperatures and then drop a strip of photographic film into each tube.
Start a different stopwatch as the each strip goes in and label them so you do not get confused. Wait.
Keep checking the baths at regular intervals and make sure that the entire protein layer from the film is gone before stopping the watches.
Once all of the watches have been stopped, record the results, wash out the tubes and repeat twice.
Once you have done the experiment three times then work out the averages and show the trend in a graph.
Below I have drawn a diagram of how to set up the experiment.
Safety:
When using water baths be careful not to burn yourself and do not put the trypsin near your eyes or mouth.
