Fair test:
Each test tube must be placed in the water bath for exactly five minutes.
5 cm3 of starch and diastase solution must be added to each test tube.
Use one glass rod for each tube and a separate one for the iodine solution.
Add one drop of iodine solution to each starch-diastase mixture
The Independent Variables
Independent variable will be the temperature of the enzyme.
The controlled Variable In this case will be the volume of starch and diastase solution and the timing.
Safety:
Goggles must be worn at all times as iodine solution can cause serious damage to the eyes.
Long hair and ties should be tied back, so it’s easier to work. And also ties should be removed
Plan:
Equipment required:
5 test tubes
Test tube rack
Labels or wax pencil
Pipette (5 cm3)
White tile
6 Glass rods
Starch solution (substrate - 25 cm3 or 1%)
Water bath maintained at 25° C, 40° C, 60° C and 100° C
Diastase solution (enzyme- 25 cm3 or 1%)
Iodine solution
Label five test tuves: from room temperature (control) 25° C, 40° C,60° C and 100° C. To each test tube add 5 cm3 of diastase solution.
Place each tube in the appropriate water bath for exactly five mintues. The first tube should be kept at room temperature (25° C).
3)At the end of the five-minute peroid remove the tubes from the water baths, and cool them rapidly to room temperature.
Now add to each tube 5 cm3 of starch solution and mix with clean glass rod
At intervals of one minute test each tube for the presence of starch: with draw one drop of starch-diastasemixute, place ir on a white tile. And add one drop of iodine solution. Use on glass rod for each tube and a separate one for the iodine solution
Results:
Discussion
From my results I can say that the optimum temperature for the enzyme is 40 because the enzyme worked effectively because it changed all of the starch solution into new products. The starch therefore was not detected using the iodine solution. At 100 ° C the starch was present as well as at 60° C
Conclusion
I conclude that at 40 degrees the enzyme is more effective the Optimum temperature of diastase is 40° C and denatures at temperatures exceeding 40° C. My results proved that what I predicted is correct In my prediction I said that starch will be present at 100 ° C. This came out to be right as the enzyme denatured at 100 ° C. Because of the enzymes structure at the binding site was destroyed there fre no rewactions could take place. This meant that the starch molucles no longer fitted into the active site of the enzyme and thus it was not broken down and so it was still present in the iodine solution This happened again same at the tempoeratue of 60 degrees but I think the enzyme must of produced sum products At 25 ° C, the reaction is slow as the enzyme yet at this point does not encounter the energy required to speed up the interaction between the enzyme and substrate.But, some starch is broken down therefore which meant that in the iodine test starch was present.
Evaluation:
The experiment worked well overall, I think the experiment could be preformed more effectively and I could get a better accurate results. For example using iodine although iodine is a good indicator of whether or not starch is present, it does not provide us with accurate information about the concentration of starch present. I think its more suitable use a colorimeter. This device provides an indication of how deep a colour is, and could have been used to measure the colour concentration of the samples throughout the experiment. This would have told me how much the enzyme had converted starch or if it didn’t at all.
I think my results were minor to support this conclusion, but if I had the chance to re experiment and investigate further on the effect of temperature on the breakdown of starch I would take more results focusing on the temperatures between 30 degrees and 50 degress trying to find out the optimum temperature of the diastase enzyme.
