Investigating the effect of the enzyme amylase on the breakdown of starch

Concentration

The concentration of Amylase affects the speed of a reaction because the required energy for the reaction to take place is lowered so the energy already in the saliva will be enough to breakdown the starch.

The rate of an enzyme – controlled reaction is dependant on the number of successful collisions between molecules of enzyme and substrate(s). The rate of an enzyme – catalyzed reaction is directly proportional to the concentration of enzyme, as long as there is excess substrate.

Heat

When enzymes are mixed with heat the rate of reaction is increased as shown in the graph. But as also shown in the graph that if the temperature exceeds a certain (centigrade) the enzyme will denature and the substrate will no longer fit.

Saliva contains an enzyme called amylase this starts to digest starch to sugar. This graph shows the rate of reaction when temperature is increased:

PH

The effect of changes in the PH on the rate of an enzyme- catalyzed reaction I shown in the graph below. The enzyme molecule changes its shape over the range of PH values and only over a narrow PH range is the active site correctly formed.

Substrate Concentration

For a fixed enzyme concentration, the rate of reaction is affected by increases in substrate concentration as shown in the graph. An increase in the number of substrate molecules (region A) increases the number of successful enzyme- substrate collisions, so the rate of reaction is faster. At higher substrate concentrations (regions B) the active site of every enzyme is occupied at any given moment.

I have chosen to do the investigation of “The effect of the enzyme amylase of the breakdown of starch” using the factor concentration of amylase. I have chosen this factor simply because it is the easiest and fastest way to undertake this investigation which will give me more time to make it a more accurate experiment.

(4)

To carry out this experiment I will need:

Tripod

Bunsen Burner

Heat mat

Large beaker

Small beaker

Syringe

Pipette

Spotting tile x2

Test tube x2

Test tube rack

Goggles

I will also need these substances to carry out the experiment:

Iodine

Starch (1.0)

Amylase (0.5,1.0,1.5)

(5)

Method

1.Set out equipment how was shown

2. Put Iodine in spotting tile

3.Mix amylase and starch while starting the stop clock.

4. Every 15secs put a drop of mix on a different dimple ( You must keep on doing this until it turns the same color as it was before)

5.Now put the mix in a test tube

6. Put 2ml of benedicts solution in the test tube.

7.Put the test tube in the beaker and heat until becomes an orangey pinky color.(we do this to prove that it was a glucose substrate)

“Make sure when repeated all equipment is cleaned thoroughly”

Here is a quick sketch of what your equipment should look like when set up:

The summary of the equipment is according to what can be found in the schools equipment.

The syringe and pipette must measure to 1.0ml and the stop clock must measure up to m/s

(6) To make this a fair test there are not many precautions I must take but here is a bulleted list.

• Make sure you have the same amount of substrate each test.
• Make sure all test tubes, beakers and spotting tiles are cleaned thoroughly.
• I will have to be quick off the mark for with the stop clock.

(7) There are few safety precautions needed:

• Safety goggles while using Bunsen burner.
• Heat matt for Bunsen burner.
• Be careful while dealing with Iodine because it is irritable to skin and stains clothes.

(8) This is the table I will be taking my results to:

(9) If I have enough time I will go through this whole table twice so that I an compare the results and write an average for each.

Prediction

Form this investigation I think that I will find out that the break down of starch will increase in speed each time I increase to concentration of amylase.

When I increase the concentration of amylase I think the rate of reaction will escalate to resulting to the break down of starch increasing and the time taken decreases.

If you double concentration the time taken to breakdown a known amount of starch halves, as shown:

Amount of concentration

E=Enzymes

S=Substrate

As shown above the amount of active sites is increased when the concentration is increased.

“Resulting there being more active sites to breakdown the starch”

(11) I am going to carry out a preliminary test to make sure that my method of “Investigating the effect of the Enzyme Amylase on the breakdown of starch” works.

These are the results I obtained in my preliminary test.

From this preliminary practice test I have decided that I have no need to charge my method. Because the results came out accurately.

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Analyzing Evidence

 I have chosen a number of ways to show my obtained evidence one of which is the results table on the page before another one is the line graph on the page 9.

        By looking at my results I have noticed that as I increased the amylase substrate the speed of the breakdown by starch increased. This is because when the substrate is increased the amount of active sites increases which allows more active sites to attach to the starch and break it down.

As shown in the diagram below:

My results have accurately proved this fact and all of my benedicts tests proved that there was glucose present because they all turned a light brown orangey color.

        My conclusion matched my prediction perfectly because in my prediction I said that the time taken would decrease as the amylase substrate increased. And as you can see by results that has been proven. And my results have been proven to be taken accurately because of the benedicts tests showing positive and also the amount of times I repeated the tests.

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Evaluation

1. My investigation was about finding out the rate of reaction when I put a mixture of amylase and starch with Iodine. This was would verify the effect of the enzyme amylase on the breakdown of starch. I expected the Iodine to first turn black and then eventually turn back to its original color. This method was a good way of measuring the rate of reaction of enzymes breaking down starch.
2. I think my way of carrying out the experiment was a good because it proved the fact that when I increased the concentration of amylase, the time taken for the active sites to break down starch decreased. The only bad thing I can think of about the way I carried out the experiment is the fact that u are not always sure that the Iodine has returned to it original color which sometimes made the results a bit inaccurate.
3. If I was to start the experiment again the only thing I would improve was the mixing from the mixture of Iodine. Because sometimes I could not be totally sure that the Iodine had returned to its original color.
4. My results were accurate. Proved by the line graph because the line justifiably had a clear straight run through the results pin pointed. But I did have to repeat many results taken. The time taken to breakdown starch was accurately decreasing when I increased the concentration of amylase.
5. There were many results I was forced to re-do. Because the result did not suit the rest of them this happened because sometimes I would be 1 dimple to late to stop the clock or 1 dimple to early and because we only put 1 drop of the mixture in a dimple every 15 seconds. That extra or less 15seconds could make a very big difference!