Required Practical 5 - Enzymes

Describe how you would investigate the effect of pH on the rate of reaction of the amylase enzyme

• Place starch solution, amylase solution and buffer solution in a water bath at 25°C for a few minutes

• Combine solutions and add a drop of the mixture to iodine solution on a tile

• Add the mixture to iodine solution drops on the tile at fixed 30s intervals until the iodine solution remains brown (does not turn blue-black)

• Calculate the rate of reaction using 1 / time taken for solution to remain brown

• Repeat at different pH values using different buffer solutions

• Plot graph of rate (y) against pH (x)

Which enzyme catalyses the breakdown of starch in the human digestive system?

Amylase - catalyses breakdown of starch to maltose

Why must samples be left in the water bath before solutions are mixed?

To allow temperature to equilibrate

What is a buffer solution?

A solution which can resist changes in pH