Required Practical 5: Effect of pH on Amylase Flashcards
1
Q
What does amylase do?
A
Amylase breaks down starch molecules into simple sugars
2
Q
What is the first step of the required practical?
A
- Place one drop of iodine solution into each well of a spotting tile
3
Q
What is the second step of the required practical?
A
- Take three test tubes and in the first test tube we add 2cm^3 of starch solution, in the second test tube we add 2cm^3 amylase solution and in the third tube we add 2cm^3 of pH 5 buffer solution
4
Q
What is the third step of the required practical?
A
- Place all three test tubes in a water bath at 30 degrees. Leave them for 10 minutes to allow the solutions to reach the correct temperature
5
Q
What is the fourth step of the required practical?
A
- Combine the three solutions into one test tube and mix with a stirring rod. Return to the water bath and start a stopwatch
6
Q
What is the fifth step of the practical?
A
- After 30 seconds, use the stirring rod to transfer one drop of solution to a well in the spotting tile which contains iodine
- The iodine should turn blue-black showing that starch is present
7
Q
What is the sixth step of the practical?
A
- Take a sample every 30 seconds and continue until the iodine remains orange
- When the iodine remains orange, this tells us that starch is no longer present
8
Q
What is the seventh step of the practical?
A
- Repeat the whole experiment several times using different pH buffers
9
Q
What are the problems with this experiment?
A
- We are only taking samples every 30 seconds
- This means that we only have an approximate time for the reaction to complete
- We are looking for a time when iodine does not turn blue-black, this is not always obvious
10
Q
What ways can we use to fix these problems?
A
- Taking samples every 10 seconds
- Ask several people to look at the spotting tile and decide when the reaction has completed.
