To Try To See If The Temperature Affects The Rate In Which Amylase Breaks Down Starch Into Maltose.

Science investigation

Aim: To try to see if the temperature affects the rate in which Amylase breaks down starch into maltose. In this reaction starch is the substrate and maltose is the product. Amylase is an enzyme, Enzymes, also called catalysts, are in living things and there are thousand of them. Enzymes break down food by the active site on the Enzyme forming a chemical bond with a substrate and then water attacks the substrate until it is hydrolysed (split in 2).

Equipment:

Boiling tubes

Timers/ stopwatch

Starch

Solution of Amylase - colourless

Thermometer

Spotting tiles

Pipette

Water baths (at different temperatures)

Iodine

Measuring cylinder

Method:

1. Collect equipment and set up as shown in diagram.

2. Fill a boiling tube with 10cm of starch and another with 5cm of enzyme.

3. Place both in a water bath at 20 degrees.

4. Wait until both test tubes reach equilibrium, test this with a thermometer.

5. Fill 30 spots on the spotting tile with 2 droplets of iodine. 30 spots are enough for 15 minutes, which is the maximum time the reaction will be allowed to run for. After this a result of no reaction will be recorded.

6. Place the 10 cm of starch and 5cm of enzyme in one boiling tube. Leave this tube in the water bath in order to maintain the current temperature.

7. Shake the tube once

8. Take 2 droplets of the starch/ enzyme solution and place in one spot on the tile.

9. Repeat this every 30 seconds until the solution turns the same colour as the control. In between the 30-second intervals wash the pipette in water, which is neutral in order to wash any remaining solution of the previous droplets.

10. Repeat this 3 times for reliability and accuracy.

11. Do this for 30 degrees and 40 degrees as these are an increase in 10 degrees and 40 degrees is also close to body temperature. Also repeat the experiment at 50 degrees and 100 degrees. The reason for testing 50 degrees is that above 50 degrees the enzymes are denatured and stop working because they are proteins and because the shape of enzymes are changed and can no longer combine with the substance. 100 degrees should be tested as a control. This will test whether a substance is an enzyme as if a substance can still carry out its reaction after it has been heated to boiling point, it cannot be an enzyme.

Variables: the first variable is the type of enzyme used; this will always be amylase, as other enzymes, such as lipase, will react differently in different temperatures. Also, an enzyme, which normally acts on one substance, would not act on a different one because it would be the wrong shape. This means an enzyme that breaks down starch to maltose would not also break down proteins to amino acids. The volume of the solution should also be kept the same, 15cm, 10cm, of starch and 5cm of enzyme. The correct quantities should always be used in order to have a fair test, as an increase in the concentration of enzyme molecules would affect the reaction rates. As many chemical reactions can be speeded up by a substance called a catalysts. Catalysts speed up the rate of reaction without being changed itself. Almost, all the chemical reactions, which go on inside the body, are controlled by catalysts. The catalysts, which are found in living organisms, are called enzymes. The ph of the starch is also important, the optimum ph for the reaction is ph7, and this is