How does temperature affect the rate at which amylase works.

How does temperature affect the rate at which amylase works

Introduction

For this piece of coursework, we have been asked to investigate the affect of amylase on starch. Amylase is an enzyme that helps speed up the digestion of starch. Starch is a carbohydrate; that is made up of a chain of glucose molecules.

Variables

In this experiment there are many variables, these are the things that you can change to vary the outcome.

I have found that in order to change the outcome of this particular experiment, I could change the:

Temperature (of amylase) – input variable
Volume of starch – 5cm3
Volume of amylase – 6 drops
Time – outcome/independent variable
Mixing – decide whether to mix or not

As my input variable I have chosen to change the temperature. The outcome/independent variable is the amount of time needed for the amylase to digest all the starch.

Prediction

I think that the amylase will start to work faster on breaking down the starch when the temperature increases. However after about 37degrees the amylase will start to slow down the process of breaking down the starch. I think that as the temperature of the amylase is increased; the particles will have more energy and collide more frequently with the substrate. This will result in the process of the amylase breaking down the starch being speeded up and should take less time. However, I think that after a certain temperature the active site of the amylase will become denatured and will not be able to fit with the substrate, therefore the process of breaking down the starch will not occur.

After the experiment has taken place, to be able to find out if all the starch has been digested into glucose I will use my previous knowledge and carry out an iodine test. This will indicate if any traces of starch are left in the substance, and I will be able to tell if the digestion has taken place. I will put all my results into a table.

Apparatus

Beaker
Thermometer
Bunsen Burner
Solution of starch
Solution of amylase
Stop Clock
Iodine
Pipette x 3
Spotting Tile
Water
Boiling tube
Measuring cylinder
Tri-pod
Heat proof mat

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Apparatus

Beaker
Thermometer
Bunsen Burner
Solution of starch
Solution of amylase
Stop Clock
Iodine
Pipette x 3
Spotting Tile
Water
Boiling tube
Measuring cylinder
Tri-pod
Heat proof mat

Diagram

Method

Measure the amount of starch needed and amylase.
Put a couple of drops of iodine in a spotting tile.
Heat the amylase to the right temperature, if you need to use a Bunsen burner, when it is at the right temperature add the starch to it. Start the stop watch.
Every 30 seconds use the pipette to get a couple of drops of the mixture and put it into one of the solutions of iodine.
If the iodine turns black, you have to repeat step 4 until the solution stays the same colour.
When it stays the same colour stop the stop watch. What ever the time is, that’s how long it took the amylase to brake down the starch.
Repeat this experiment for other temperatures.

Why use Starch?

For this experiment I will be using starch solution. I will be using it because this is what is broken down by amylase in the human body.

Why use iodine?

I will be using iodine because when starch is added to it, it turns from being an orange colour to a dark blue/black colour. By using this I will know when there is no-longer any starch present because the colour of the iodine will not change.

How is the method fair?

This is a fair method because I am going to change the temperature of the water in the beaker. The amount of water in the beaker will always be the same. I will always remove a drop of the mixed solution every 30 seconds.

Why repeat the experiment?

I will repeat the experiment so I can get the most accurate results possible. I will be able to get these accurate results by finding the average for each temperature.

What temperatures will I test?

My first temperature will be room temperature, and then I will increase this by 5 until I reach my highest temperature of 80C.

Results Table

Analysing and Conclusion

We can obtain evidence by looking at the graph that has been drawn. We can see that as the temperature increases the time decreases until the enzymes start to denature and the time increases again. The line of best fit which is on the graph tells us that the optimum temperature for this amylase is 55C. This suggests that the amylase was resistant to denaturation. The amylase we used was bacterial which is substantially higher than human’s amylase.

In my prediction I predicted that the optimum temperature would be 37C but I was incorrect because the right optimum temperature was 55C.

Evaluation

The procedure we used worked well however we did come across some problems. We found having two people working on the one experiment gave us inaccuracies. For example, when we put the drops of iodine into the spotting tile one person would put small drops in and then another person would put bigger drops. This made the colour of the solution lighter and darker. So that made the judging of the colour difficult because one person would say that the experiment was finished then another person would disagree. Then we could finish the experiment at one colour and on another finishing colour may be lighter or darker.

Due to these inaccuracies, we had 4 results that didn’t fit into the line of best fit. To improve the experiment I think we would need to be more accurate. To do this we would have a set shade of colour at which we’d finish the experiment and a set amount of drops of the iodine solution in the spotting tiles. Also we should have done higher temperatures because we didn’t do a higher enough temperature.

This experiment wasn’t completely reliable. This is because the temperature of the solution was not consistent. The temperature would decrease after we had heated it to the correct temperature we needed. The way to put this right would be to use an electrically controlled water bath we stay at the same temperature. This way results would be more reliable and perhaps more of them would fit the graph. Also it wasn’t reliable because the two trials we did the results were totally different.