Investigating the effect of pH on enzymes [EXPERIMENT]

Question 1

What is amylase?

Answer 1

Amylase is an enzyme that catalyses the breakdown of starch and maltose.

Question 2

What do you use to detect starch?

Answer 2

Iodine solution - if starch is present, the iodine solution will change from browny-orange to blue-black.

Question 3

What is the first step to investigating how pH affects amylase activity using iodine solution?

Answer 3

Put a drop of iodine solution in every well of a spotting tile

Question 4

What is the second step to investigating how pH affects amylase activity using iodine solution?

Answer 4

Place a Bunsen burner on a heat-proof mat and a tripod and gauze over it.
Put a beaker of water on top of the tripod and heat the water until it’s 35 degrees.
Use a thermometer to check the temperature and try and keep this temperature throughout the experiment.

Question 5

What is the third step to investigating how pH affects amylase activity using iodine solution?

Answer 5

Use a syringe to add 3cm³ of amylase solution and 1cm³ of a buffer solution with a pH of 5 to a boiling tube.
Using test tube holders, put the boiling water into the beaker of the water and wait for five minutes.

Question 6

What is the fourth step to investigating how pH affects amylase activity using iodine solution?

Answer 6

Using a different syringe, add 3cm³ of a starch solution to the boiling tube.

Question 7

What is the fifth step to investigating how pH affects amylase activity using iodine solution?

Answer 7

Immediately mix the contents of the boiling tube and start a stopwatch.

Question 8

What is the sixth step to investigating how pH affects amylase activity using iodine solution?

Answer 8

Take continuous samples of the solution and record how long it takes for amylase to break down all the starch.
To do this, using a pipette, take a sample of the solution every ten seconds and put a drop into a well.
When the iodine solution remains browny-orange, the starch is no longer present.

Question 9

What is the seventh step to investigating how pH affects amylase activity using iodine solution?

Answer 9

Repeat the whole experiment with buffer solutions with a range of pH values to see how the pH affects the time for the starch to be broken down.

Question 10

How do you calculate the rate of reaction?

Answer 10

Rate(unit time) = 1000/time(seconds)
So for example, if it took 50s for the amylase to break down the starch, the equation would be:
1000/50 = 20sˉ¹

Question 11

How do you calculate how much something has changed over time?

Answer 11

Amount product formed = change
Rate(cm³ sˉ¹) = change/time(seconds)
So for example, if 24 cm³ of oxygen was released in 50s, the equation would be:
24cm³/50s = 0.48cm³ sˉ¹