How Does Temperature Affect the Action of Amylase on Starch?

Variables:

• Temperature – The temperature will be changed during this experiment. I will be changing the temperature at 10˚C intervals starting at 20˚C.
• Time – The time taken to break the starch down according to the temperature will be recorded.
• The volume of Amylase, Iodine, and Starch – This could be changed but to make it a fair test these will be kept the same all through the experiment.

Method:

1. The spotting tile will have the different times written over the hollows.(starting at 0, with 15 second intervals)
2. 30cm³ of Amylase will be measured out using a measuring cylinder. I will hold this at eye-level to check it is accurate.
3. The contents of the measuring cylinder will be divided up into six test tubes with 5cm³ in each test tube.
4. The test tubes will then be put into water baths of the different temperatures (20˚C, 30˚C, 40˚C, 50˚C and 60˚C, 70˚C).
5. The 2cm³ of iodine will be measure using the pipette and put on the spotting tile in the hollows.
6. The amylase solution will be taken out of the 20˚C water bath and checked with the thermometer to see if the temperature is at 20˚C.
7. 2cm³ of the amylase solution will be measure and added to a beaker.
8. 10cm³ of starch will be added to the amylase solution using the measuring cylinder.
9. The amylase and starch solution will be drawn in the syringe.
10. The amylase starch solution will be added 1cm³ at a time to the iodine hollows starting at the 0.
11. The stopwatch will be started when the amylase starch mixture is added to the hollow with 0 over.
12. Another 1cm³ will be added to the 15 hollow after 15 seconds. This will be continued through the tiles every 15 seconds.
13. The stopwatch will be stopped when the iodine turns from a blue/black colour back to brown.(using untouched iodine to check the colour)
14. The time will be recorded.
15. Steps 6-13 will be repeated with the test tubes in the 30˚C, 40˚C, 50˚C 60˚C and 70˚C waterbaths.
16. The results will be recorded in table.
17. The whole experimented will be repeated three times for accuracy and to find an average.

Results

Analysis

My results show that as the temperature got higher, the amylase broke down the starch quicker. This because heat gives molecules more energy, and causes them to move around faster and crash into other molecules harder. The amylase molecules will crash into more starch molecules in a shorter space of time increasing the chance of more successful collisions. In my experiment the enzymes didn’t denature. This is probably because I didn’t do a temperature that was high enough. I think my graph doesn’t show typical results because 40˚C isn’t the lowest time, and at 60˚C and 70˚C produced results when I thought it would denature.

Evaluation

I think my experiment could have had a few changes to make the results more accurate. The temperature of the waterbaths was a problem because even though they were set to the temperature that I wanted to test, when I tested the temperature with thermometer the temperatures where different (e.g. the water that was supposed to be at 30˚C was at 35˚C). I don’t know why this happened. To make the temperatures correct I ran the test tubes with amylase in under the tap until the temperature was correct. My results weren't entirely what I expected because 40˚C wasn’t the optimum temperature like I was expecting it to be. This was an anomalous result. I think if I did more results and averaged it out it might have worked out with the shortest time.  Also I expected the enzymes to denature at 60˚C but it never, the amylase was quicker to break down the starch. At 70˚C the amylase broke down the starch slower. To get the enzyme to denature I should have done a higher temperature. I think that overall I worked as accurately as I possible could. If I were to do the experiment again, I would use higher temperature so that the enzymes could denature, and I check the temperature of the waterbath was accurate instead of trusting on the dial.

By Siobhan Mitchell 10A/PK