An Experiment to show how different solutions react with agar jelly. Discussion.

An Experiment to show how different solutions react with agar jelly.

Discussion.

I predict that the amylase that will be boiled will not digest the agar jelly well, as the enzymes will become denatured with the heat extreme. This causes it’s 3D structural strength and shape will be lost. The enzymes active site shape is changed, causing the enzyme to become inactive.

From my own knowledge I know that amylase is present in the mouth, the first stage of starch digestion.

I believe the water solution will also not digest the starch jelly well as it hasn’t any enzymes to digest the agar.

From scientific knowledge we know that amylase works best/at an optimum rate in alkaline conditions, so the solution of amylase and alkaline solution should do the best.

Extremes of pH can also cause denaturing of the enzymes. Depending on the pH of the acid and amylase solution, the result may be better than water, and boiled amylase, if not poor as well.

We know when denaturing occurs, the shape of the active site is changed, so it cannot form enzyme substrate complexes, so becomes inactive. I believe this will happen with the boiled amylase, and depending on the pH of the acid, may happen to the acid and amylase solution.

From the results table and graph we can see that the Amylase and acid solution created the largest clear zone by 12.2mm. Water created the smallest clear zone, and Amylase and alkaline, and boiled amylase we the two results in the middle, around the 15mm clear zone size.

From the graph, and from scientific knowledge we can explain why the results/size of the clear zones differ, depending on the different solutions added to the agar jelly.

Amylase-this solution caused the largest clear zone, this may have bin so as the enzyme was not tampered with, or added to any other solution.

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From the graph, and from scientific knowledge we can explain why the results/size of the clear zones differ, depending on the different solutions added to the agar jelly.

Amylase-this solution caused the largest clear zone, this may have bin so as the enzyme was not tampered with, or added to any other solution.

Amylase and Alkaline-this solution created the second largest clear zone; Also from the results we can see that amylase and acid solution created a smaller clear zone, therefore is not as good at digesting starch as amylase and alkaline. This shows that the enzyme amylase must work better in alkaline /high pH conditions. I expected it to create the largest zone, as amylase is proven to work better in slightly alkali conditions.

Amylase and Acid-This solution was fourth best at digesting the agar jelly, this shows that amylase does not work as well in acid conditions. Enzymes can suffer denaturisation as a result of extreme pH, this may have occurred, resulting in the smaller clear zone created.

Water-This solution was the poorest at digesting the agar jelly. In reality water shouldn’t have digested any of the agar, as it has no enzymes.

Boiled Amylase-this solution was third best at digesting the agar. Despite this we know that when enzymes are exposed to extremes in temperature that they become denatured, as their molecules gain kinetic energy, and internal bonds, such as the hydrogen bonds can be easily broken. The denaturing refers to the 3D shape that is lost, as they are proteins. Denaturing the enzymes can cause them to become inactive.

Not many of the results match what I expected to occur.

Results

(mm)

Solution type

From the graph we can see that from 1 being the best and 5 being the least good, how each solution faired digesting the agar jelly;

1.Amylase

2.Amylase in alkaline

3. Boiled amylase

4. Amylase in acid

5.water

Explanation

An explanation some of the unexpected results can be linked to the conditions under which the experiment took place.

Bacteria are the main cause to the unexpected results. Bacteria in various ways, in the hole punching of the paper, landing of the paper from in the air, off the apparatus use, and off our one fingers may have contaminated the paper. And as a result they began to release amylase onto the agar jelly, which caused various clear zones that were unexpected and may have caused some clear zones to appear larger than they should.

A clear example of this is the clear zone created by water. This in theory should not have caused a clear zone as no enzymes were present, but bacteria in the water fed on the agar, causing a clear zone.

Another way that bacteria could have affected the results is that the petri dish lid was taken off to place the paper circles with each solution on. Airborne bacteria could have landed on the agar jelly and inhabited it, jeopardising the results.

They were apparent to the eye, seen as mould formations onto of the agar.

For this experiment to work properly it would have to be carried out in sterilised laboratory conditions, where bacteria is not apparent.

Evaluation.

When evaluating results unavoidable errors have to be taken into account.

The invasion of the agar jelly by the bacteria has affected the precision of the data collected, as the size of the clear zones cannot be taken as accurate, because we know they have been an end product of the bacteria creating amylase to break to bonds in the starch/agar jelly to use it as a food source.

This means when making a conclusion our comments will be totally erroneous. Meaning our knowledge of the effects of the different solution on the agar jelly will be incorrect.

Examples of the inappropriate conclusions made might be us being lead to believe that water is able to hydrolyse the starch bond in the agar jelly, or that the boiling of amylase/enzymes doesn’t not effect their 3-D structure, making them become inactive.

We know that both of these statements are wrong, so the results cannot be used as appropriate evidence about enzymes, and how they work.

Another error that may have occurred has got to do with the paper circles.

This is as we did not ensure that the amount of each solution on each piece of paper was equal. They we put in each solution and we taken out at around the same time. This may have led to some of the paper circles to become more saturated with solution, emphasizing the results created by them.

This would have made the measuring of the clear zones inaccurate, as some clear zone may not be as big, or as small is the amount of the solution on it varied.

On the whole I believe the bacteria was the factor, which affected the results the most. The problems with the paper circles could be made a lot more accurate, but the problem with the bacteria would be extremely hard to combat in a school laboratory.