Investigating the Factors that Change the Rate of Amylase on Starch.

Investigating the Factors that Change the Rate of Amylase on Starch

Plan -

The aim of this experiment is to investigate the factors that affect the rate in which amylase breaks down starch.

Amylase is an enzyme, which is found in the digestive system, it is used to speed up the reaction of the long chain starch molecules into smaller chains. Enzymes are biological catalysts that will speed up a reaction without them selves being changed. Enzymes are very complicated molecules that are twisted and folded into very precise three-dimensional shapes, this shape includes a dent, which is called the active site, it is exactly the right shape and size for the substrate.

E.g. starch will only fit into the amylase enzyme. When a substrate fits into an enzyme they bind and the bonds in the substrate break, this forms two new soluble molecules. Then the enzyme is ready to catalyse another reaction. Enzymes are affected by high temperatures as they are proteins and if the temperature is too high it can alter the shapes of the enzyme molecules, enzymes are damaged when the temperature reaches over 40 C. Therefore:

I predict that the optimum temperature for the amylase to break down the starch will be about 37 – 40 C. I think this because this temperature is body temperature and therefore the amylase should work best, and because most chemical reactions work best when the temperature is higher as the molecules work quicker, making it easier for a reaction to take place. However as the temperature rises over body temperature the amylase molecules will begin to get damaged and as it gets over 60 C the molecules will denature.

As the temperature decreases below body temperature I also think that it will take longer for the reaction because the amylase molecules will not have much energy and will work much slower.

To ensure that this experiment is fair I will only vary 1 variable. The variables to choose from are:

Volume of starch,
Volume of amylase,
Time intervals,
Temperature.

I have chosen to vary temperature. To ensure that all the other variables stay the same I will carefully measure the quantities of the starch and amylase solution’s using a ...

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As the temperature decreases below body temperature I also think that it will take longer for the reaction because the amylase molecules will not have much energy and will work much slower.

To ensure that this experiment is fair I will only vary 1 variable. The variables to choose from are:

Volume of starch,
Volume of amylase,
Time intervals,
Temperature.

I have chosen to vary temperature. To ensure that all the other variables stay the same I will carefully measure the quantities of the starch and amylase solution’s using a syringe as even small variations could affect the results. I will also use a timer to guarantee that I put the amylase and starch solutions in every minute.

To carry out this investigation I am going to need the following:

Dimple trays,
Syringe,
Amylase,
Starch,
Timer,
Water baths,
Ice,
Thermometers,
Test tubes,
Teat pipettes.

I have chosen to use water baths as they are very effective and the temperature is more accurate than using a Bunsen burner. The ice is for the colder temperatures under 10 C.

To do this experiment I will first have to pour 2cm of amylase solution and 2cm of starch solution into two separate test tubes and put them in a water bath. Then I will place a drop of iodine into each dimple on the dimple tray. After a few minutes of the amylase and starch solutions in the water bath I will pour the starch into the amylase and with a teat pipette place a drop of the solution into one of the dimples on the dimple tray which contains iodine on, I will then start the timer. After 1 minute I will put another drop of the solution into another dimple on the tray. I will carry on adding a drop after every minute until the tray is full.

From the trial test I did, I decided to use 2cm of amylase solution and the same amount for the starch solution. After every minute I will put 1 drop of the solution into one of the dimples. I also decided to do the temperatures: 4 C, 25 C, 40 C, 50 C and 70 C. I will use ice to get below 10 C and use a water bath to get the temperatures above room temperature. I will stop each experiment when the iodine stays a brown/orange colour.

I have also decided to carry out the experiment twice and calculate the average to ensure there are no abnormal results.

Results

Conclusion –

From my results and graph I can see that when the temperature is very low the amylase does not react with the starch, but as the temperature rises the time taken for the amylase to break down the starch decreases. The quickest time for this to happen is 50 C because that is when the amylase has the most energy and works the fastest. However as the temperature goes over 50 C and reaches 70 C I can see that the amylase is starting to denature because the time taken begins to increase.

I predicted that the optimum temperature for amylase to break down starch would be about 37/40 C, because this is body temperature and enzymes work best then. I also predicted that as the temperature got higher the time taken will be longer because of the enzymes starting to denature and that if the temperature got lower if would also take longer because the amylase doesn’t have as much energy and therefore would not be as fast.

So to an extent my prediction supports my results since as the temperature increases the time taken for the amylase to break down starch decrease up to a certain point, after this point it would start to increase. However I predicted that the optimum temperature would be around 40 C but was actually around 50 C.

However from my results I am not able to find that much of a relationship other then as the temperature rises the time decreases until the temperature reaches over 50 C.

Evaluation –

I think that my experiment went quite well but a few of my results weren’t what I thought they would be as the graph shows that the optimum temperature is 50 C when in fact it should be 40 C, the 50 C time should have been higher then the 40 C one, and the graph should have been more of a ‘U’ shape rather than the shape it is.

I could have improved the experiment by taking the pH level instead of just judging it by the colour as I could have easily stopped on slightly different colours. The amylase should have also been kept in each water bath for longer, maybe for 30 minutes so that the amylase had been completely affected by the temperature before it was added to the starch.

I also think that I should have done more temperatures with perhaps 10 C between each temperature to get clearer results. But overall I feel that my experiment was designed quite well.