Enzymes practical

Question 1

Aim of practical

Answer 1

Aim: To investigate the effect of pH on the rate of reaction of amylase
You will:
Use the enzyme amylase to breakdown starch at a range of pH values, using iodine solution as an indicator for the reaction occurring

Use a continuous sampling technique to monitor the progress of the reaction

Question 2

1 step

Answer 2

Place single drops of iodine solution in rows on the spotting tile

Question 3

2 step

Answer 3

Label a test tube with the pH to be tested
Use the syringe to place 2cm3 of amylase in the test tube

Add 1cm3 of buffer solution to the test tube using a syringe

Use another test tube to add 2cm3 of starch solution to the amylase and buffer solution, start the stopwatch whilst mixing using a pipette

do separately till you get to each substance to 30 degrees then add together

Question 4

3rd step

Answer 4

After 10 seconds, use a pipette to place one drop of the mixture on the first drop of iodine, which should turn blue-black

Wait another 10 seconds and place another drop of the mixture on the second drop of iodine

Question 5

4th step

Answer 5

Repeat every 10 seconds until iodine solution remains orange-brown

Repeat experiment at different pH values –
the less time the iodine solution takes to remain orange-brown, the quicker all the starch has been digested and so the better the enzyme works at that pH

Question 6

Improvements

Answer 6

A colorimeter can be used to measure the progress of the reaction more accurately; with a solution containing starch being darker and glucose light (as a result of the colour-change of iodine) – this will affect the absorbance or transmission of light in a colorimeter

to stop human error

lower the interval you add with pipette may be too long to accurately find the time taken for starch to be
completely broken down.

Question 7

What can you relate this reaction to

Answer 7

an relate this to changes in the active site of the enzyme when it has denatured, or if it is a low temperature, relate it to the amount of kinetic energy the molecules have.

Question 8

Safety measures

Answer 8

Be careful using hot water.

If using a Bunsen burner tie long hair back and wear goggles.

or heater