Enzyme Investigation - page 2
Keywords: Science Coursework Enzyme Investigation Chemistry Biology
By Jenny on 02/07/2009
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 2 of 3 pages: 1 2 3
(2)
• Stop watch
• Measuring cylinders (2)
• Amylase solution
• Starch solution
• Iodine
• Water
• Goggles
Diagram of Equipment
Method
1. Put on the Safety Goggles.
2. Get all the equipment.
3. Measure 3 ml of amylase into one of the measuring cylinders using a pipette.
4. Measure 3 ml of starch into the other measuring cylinder using the other pipette.
5. Pour the amylase into the one test tube and the starch into the other.
6. Put 5 drops of iodine into the starch.
7. Fill the beaker with water to the half way mark adding hot and cold water until the thermometer shows it is 30ºC (you may have to add more hot water to keep the water bath at 30ºC).
8. Add the amylase to the starch solution (making sure that you keep the starch test tube in the water) and starting the stopwatch as you do so (you will probably need some one else to do the stopwatch).
9. Stop the stopwatch when the blue colour disappears and record the time.
10. Now do the same thing again 3 times (to make sure you get an accurate result).
11. Finally, repeat the whole thing but with the water bath heated to first 40ºC, 50ºC, 60ºC and then 70ºC (do the experiment 3 times for each temperature to ensure you get an accurate result).
Results Table
Time taken to clear (seconds)
Temperature (ºC) 1 2 3 Average (1+2+3)/3
30 60 73 80 71
40 22 28 26 33
50 6 2 5 4
60 1 1 1 1
70
Didn’t clear
Analysis
First my graph curves downwards then as it gets towards the bottom of the graph the curve gets very close to zero before it suddenly curves very steeply upwards. This is because as the temperature rises the reaction time gets smaller, then the bottom of the curve is the optimum temperature where the reaction time is quickest and the steep upwards curve at the end is where the enzyme is denatured and can no longer react with the substrate.
It turned out that while the rate of reaction got faster the higher the temperature, the optimum temperature was actually 60ºC and the enzymes were denatured and wouldn’t work at around 70ºC. This happened because enzymes don’t work as well when they’re below their optimum temperature and then gradually get better as the temperature increases. However, after they’ve passed their optimum temperature they get distorted (denatured) and their active site doesn’t fit the substrate, so they don’t work at all.
Evaluation
I think that my experiment was fairly accurate as I repeated it three times at each temperature, but there are several errors that I have identified in my results. Firstly the results
Last 5 comments…
There have been no comments posted for this article, but you need to register if you want to be the first!