How differing concentrations of enzymes (in this experiment the enzyme amylase was used) affect the rate of breakdown of its substrates (in this experiment starch was used).

Theory

Enzymes are specialized organic substances, composed of polymers of amino acids that act as catalysts to regulate the speed of the many chemical reactions involved in the metabolism of living organisms. Substrate is the substance that is acted upon by an enzyme.

The enzyme amylase was used in this experiment in varying concentrations. This type of enzyme is contained in the saliva and small intestines and pancreas. Starch was the substrate used. It is a complex sugar produced by plants during photosynthesis, which can be broken down into maltose and glucose.

Objective of the Experiment

This experiment answers the question how differing concentrations of enzymes (in this experiment the enzyme amylase was used) affect the rate of breakdown of its substrates (in this experiment starch was used).

Hypothesis

Our prediction was that the higher the concentration of amylase, the faster the breakdown of starch.

As enzymes catalyze chemical reactions, the higher the concentration the faster the chemical reaction. As the concentration of starch was kept constant (1%) the varying concentrations (1%, 0.8%, 0.6%, 0.4%, and 0.1%) of enzymes would always breakdown the same amount of starch thus making the experiment accurate and more comparable.

Controlled and Independent Variables

In this experiment the concentration of 1% starch and the amount of iodine was kept the same throughout while the concentration of amylase was varied. The five different concentrations of amylase used were 1%, 0.8%, 0.6%, 0.4% and 0.1%.

Apparatus

The equipments used in this experiment were:

Stopwatch
Test-tubes
Test tube holders
Pipette
Syringes
Beakers
Spotting tiles
Iodine
Amylase (1%, 0.8%, 0.6%, 0.4% and 0.1% concentrations)
Starch (1% concentration)
Water

Procedure

The test tubes and droppers being used should be washed.

Drops of iodine (number of drops depends on the performer) should be placed on the spotting tile. All the spots can be filled up.

One drop of iodine should act as the control drop by diluting it with a drop of ...

This is a preview of the whole essay

Apparatus

The equipments used in this experiment were:

Stopwatch
Test-tubes
Test tube holders
Pipette
Syringes
Beakers
Spotting tiles
Iodine
Amylase (1%, 0.8%, 0.6%, 0.4% and 0.1% concentrations)
Starch (1% concentration)
Water

Procedure

The test tubes and droppers being used should be washed.

Drops of iodine (number of drops depends on the performer) should be placed on the spotting tile. All the spots can be filled up.

One drop of iodine should act as the control drop by diluting it with a drop of water.

Then 4- 5 ml starch (1% concentrate) should be poured into the test tube making sure that the syringe used in drawing the starch doesn’t have any bubbles inside it.

After taking the starch, the syringe should be put back into the beaker of starch.

Then 1- 2 ml amylase (1% concentrate) should be measured using a syringe, making sure that there are no bubbles.

The amylase should be poured into the test tube with starch and the stopwatch started immediately.

Right after that, the syringe used in drawing the amylase should be put back into the beaker with 1% concentration of amylase and NOT to any other beaker.

After 30 seconds the mixture of amylase and starch from the test tube should be drawn using a washed pipette and put on one drop of iodine on the spotting tile.

The control drop shouldn’t be touched.

The drop from the test tube shouldn’t be drawn too early. It should be drawn around 2 seconds before it is put on the iodine.

The amylase and starch mixture should be dropped on the iodine every 30 seconds until the time the color of the amylase starch mixture is the same as the control drop diluted with water.

The time should be recorded and the experiment repeated every 15 or 10 seconds rather than every 30 seconds with the same concentration of amylase.

Then the concentration of amylase should be changed and experiment repeated and time recorded every 30 seconds.

Then using the same concentration the experiment should be performed again and time recorded every 15 seconds.

This pattern should be followed until 0.1% concentration of amylase is reached.

Data

Table 1

Data Analysis

With each concentration of amylase the experiment was carried out twice (every 30 and 15 seconds intervals). The time taken for the starch to be broken down was almost the same in both the trials.

When the first drop of amylase and starch mixture was dropped on the iodine the color changed and turned blackish. This signaled that there was starch left in the mixture. Gradually the color lightened and was almost the same color as the control drop. At this point the timings were recorded which are presented in table 1.

The above table indicates that starch was broken down the fastest with 1% concentration of amylase. Gradually as the percentage concentration of amylase decreased the time taken to breakdown the starch increased.

The chart below proves why the concentration of amylase is inversely proportional to the time taken for the starch to be broken down.

Chart 1

In the first box, the concentration of amylase and starch is the same, so each substrate is broken down by one enzyme. In the second box the starch concentration remains the same but the amylase concentration decreases. This means there is more starch and fewer enzymes to break all of them at the same time. This pattern is followed in the rest of the three boxes.

Though it is true that as the concentration of amylase decreases, the rate of breakdown of starch also decreases; the time recorded in the table above may not be very accurate. In this experiment it was up to us to decide which drop of iodine with amylase and starch mixture was almost the same color as the control drop. This might have altered some of the results. Also the mixture of amylase and starch from the test tube was drawn a few seconds before it was dropped onto the iodine indicating that it might have caused errors in the recorded timings. As this experiment was done manually it was hard for us to drop the starch and amylase mixture on the iodine exactly at 30 seconds intervals. Therefore majority of the inaccuracies were due to unavoidable human errors.

Conclusion

The aim of this experiment was to examine the effects of increasing concentrations of amylase on the rate of breakdown of starch. After performing the experiment we can therefore conclude that as the concentration of amylase decreases, the time taken for the starch to be broken down increases while the rate of breakdown of the starch decreases (attached graphical representation at the end of the report).

Evaluation

The procedure used was quite effective. We were able to come up with reasonable results although they weren’t 100% accurate. The errors that were committed were mostly due to human limitations. These errors can only be rectified if performed by a machine. But there were some errors, which could have been avoided like the use of water bath, as it would keep the temperature constant. On the whole the experiment was pretty successful.

Improving the Investigation

As most of the errors were unavoidable human errors, it is very difficult to suggest ways of improvement. As mentioned earlier these errors are bound to happen if the experiment is performed manually. These errors can be reduced by the use of appropriate laboratory equipment. But to make the experiment more effective we should have used the water bath.