I have decided to control the temperature the experiment is done at; I will do this with a thermostatic water bath.
The factor I will have to control will be making sure that I use the same, amount of Trypsin and milk, and make sure the concentration of the Trypsin is the same.
Safety
Whilst I am setting up the experiment, undertaking it and handling the Trypsin I will wear safety goggles, as if any Trypsin gets in my eyes it will digest its way through as it is an enzyme. I will clean up any spillages and handle the beakers with care as if they are dropped they will smash.
Prediction
For my experiment I predict the rate of the reaction will increase, until they get to a point where the enzymes will not work which is when the rate of the reaction will go down again.
To the right is a graph which I got from ‘Biology For You’ textbook; this is what my results might look like:
All enzymes are proteins, at high temperatures the protein breaks down. The active site is changed, so the substrate no longer fits, the enzyme has been denatured and it no longer works
Enzyme denatured - substrate no longer fits the active site.
I will collect my results in a table like this:
This is the table that I will use to work out the rates:
Obtaining Evidence
I made my results as accurate as I could. I did this by using a 5ml measuring syringe to measure the amount of milk and trypsin, as this has a mark every 0.5ml on it so I can measure the amount accurately. I did not have any anomalous results.
Here are the results that I collected in the main table. I will plot these results on my graph:
I then converted my averages in to rate, I will plot the rates on my graph:
I have ‘360+’ in the table because the trypsin did not digest the milk after 360 seconds, this is probably because the trypsin has been denatured and it no longer works.
Analysing and Considering Evidence
I have found out that at low temperatures and at high temperatures it takes the enzymes a long time to work. At low temperatures, the reaction is slow because enzymes find it hard to work in cold conditions this is because they are used to working in about the same temperate that the body is at and 30oc is to low for the body to be at, so the enzymes find it hard to work. They do not work at high temperatures either for the same reason that the body does not work at the high temperatures. At 80oc the enzymes were denatured, this means that the substance no longer fits the active site; in other words the enzymes have been boiled and killed so can not work. This is because enzymes are proteins, and at high temperatures proteins breaks down. The active site is changed, so the substrate no longer fits, the enzyme has been denatured and it no longer works.
My graph shows that at 30oc the enzymes take a long time to react this is because it finds it difficult to work. Then at 40oc the enzymes work quite quickly, this is because they usually work in these conditions. Then as the enzymes react at 50 oc, then 60oc, 70oc and finally at 80oc they gradually take longer to react until the enzymes are finally denatured. This is because they are getting further away from the temperature that they usually react at.
My graph compared with the one in the ‘Biology For You’ text book are quite similar. They are both in the same shape and the values are about the same. Therefore, I think that my graph is quite good as they are about the same.
!Leave This Page Blank For The Graph Page!
Evaluation
Results
I did not have any anomalous results in my table or on my graph. I think that my results were correct. My results were as I expected them to be. I think my results are good enough to make a firm conclusion, as they are similar to the results in the text book, which are reliable.
Problems
I encountered some problems in doing my experiment. The biggest problem that I encountered was not being able to use a thermostatic water bath. I couldn’t use on for several reasons: there was not enough water baths for everyone to use in the class and if I did use one it would take to long to take all of my results as I would have to wait for the thermostatic water bath to get to the correct temperature each time. I solved this problem by putting the milk and trypsin in test tubes, I then put the test tubes in a beaker of water, I heated the water until the temperature of the milk and trypsin is correct, I then put the milk into the trypsin test tube and waited for it to react, I kept the temperature correct with a Bunsen burner.
Another problem was the time error in the stop clock. I would have wasted time from when I saw that the milk was digested to when I stopped the clock. This would not have wasted lots of time but it would have wasted some. I could not do anything to solve this problem.
Improvements
I could have improved my experiment by using more accurate measuring equipment, such as a burette instead of a measuring syringe. I could have used a thermostatic water bath, but this was not possible as I explained above. I could have used an electronic thermometer, as this would be more accurate than a normal one.
