Investigating the effect of temperature on the Enzyme Amylase.

Kimberley Oakley

Investigating the effect of temperature on the Enzyme Amylase

Aim:

In our experiment, our aim is to find out how temperature affects the rate of reaction with starch and amylase.

Scientific Knowledge:

Amylase is an enzyme that can be found in saliva and in the small intestine, it is very useful in breaking down molecules. As it breaks them down, it breaks them down into sugar, which can pass across cell membranes. We can see this reaction taking place by adding a couple of drops of iodine to the starch.

A solution that contains starch will turn a blue-black colour when iodine is added. But as the amylase breaks down the starch into sugars, the blue-black colour fades away. When the blue-black colour is gone, all the starch has been broken down into maltose.

How do enzymes work?

The picture below shows how enzymes work. Molecules are forever moving about, and they bump into each other. When a molecule bumps into a molecule of the right enzyme, it fits into a depression on the surface of the enzyme molecule. This depression is called the active site. The reaction takes place and the molecules of the product leave the active site, freeing it for another molecule.

Variables:

Temperature: Increasing temperature will cause molecules to move faster.

Volume: The larger volume of amylase solution there is, the more amylase molecules there will be, and so the starch will be broken down faster. If a larger volume of starch solution is used, then there will be a higher number of molecules to break down and so it will take a longer amount of time before all the starch will be gone.

Plan:

I will be investigating the ...

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Variables:

Temperature: Increasing temperature will cause molecules to move faster.

Plan:

I will be investigating the effect of temperature on the rate at which the starch is broken down into maltose.

Safety:

In this investigation, there are not many safety precautions, but we are using a water bath that can hold water up to 75 C, and we need to be careful that no burns occur. Also, we are using iodine, that can sting if it goes in the eye, but in the laboratories, there are eye washes in case any accidents occur.

Apparatus and materials:

Spotting dish
Starch
Amylase
Iodine
Pipettes
Stopwatch
Conical flask
Thermometer
Water Bath
2 test tubes

Method

Before starting the experiment, a spotting tile is prepared so that each hole has a drop of iodine in it.

An amount of starch is measured out into a 50 ml measuring cylinder. It is then put into a conical flask.

Some amylase solution is measured out (the amounts will be determined in our preliminary experiments)

This is added to the starch in the conical flask, at the same time as the amylase is added, the stopwatch is started.

Every 10s, a pipette is used to take a small amount of the mixture, it is then put into a drop of iodine in the spotting tile. If the mixture contains starch, the iodine will turn blue-black.

If there is no starch present then the iodine will stay its original colour.

When the iodine no longer changes colour, the time is recorded, as all the starch has been broken down into maltose, therefore the reaction is complete.

Preliminary experiments:

In our preliminary experiments, we determined the temperatures and the volumes of the solutions we were to use.

We decided to use 50cm of starch, and 20cm of amylase. When we mixed the two solutions together, we would start the stopwatch and use a pipette to put in a small amount of the mix into the spotting tile each time. To see how temperature affects the reaction time of amylase and starch turning into maltose, we decided to increase the temperature of the mixture by 10 C each time.

Results:

Every 10s, using a pipette, we put the amylase and starch mixture into the iodine.

Conclusion:

From my results, I can see that the higher the temperature the less time that it takes for the amylase and starch to react and produce maltose.

Detailed scientific knowledge to explain conclusion:

In my conclusion, I said how temperature decreases the time for the amylase and starch to react. This is because increasing the temperature causes molecules to move faster, this is because heat gives them more energy, and the molecules move around quicker, therefore reacting quicker.

Evaluation and Errors:

There are not many errors I could have made in this investigation, however there may be a few factors that could have had an affect on the results.

The temperature of the room may have been different, as I carried out my experiment on two different days, even though I used a water bath to control the temperatures, the room temperature may have had a small affect.

If there was a draught, that may have cooled down the mixture quicker.

Also, even though we made sure we had the correct measurements of amylase and starch, they may have been slightly different. To increase our chances of getting fair results, we made sure we used the same equipment each time.

Suggested Extension work:

For extension work, I could carry on with my experiment by testing the effect on temperature of amylase and starch at a much higher temperature, maybe 100 degrees Celsius, and to see whether once they have reached a certain temperature take the same time to react hence forth.