The Effect That Temperature Has On the Rate of the Reaction Between Amylase and Starch

Planning

Prediction

I predict that the amylase will break down the starch most effectively at 40ºc, this is because the optimum temperature for amylase is 37ºc (the temperature of the body). This means that the efficiency will decrease towards 0ºc because the molecules will have less energy and have fewer collisions so the reaction will take longer. At 0ºc, I predict that the amylase will not be able to break down the starch because they will have too little energy. Past 40 ºc the speed of the reaction will decrease dramatically because the enzymes will begin to denature to the extent that at temperatures over 60ºc the reaction will be totally ineffective. To show my predictions more clearly I have drawn a graph,

Apparatus list

To obtain my results I am going to use the following equipment;

• Test tubes ~ to heat up the amylase in
• Boiling tubes ~ to heat up the starch in
• Water bath ~ to heat both solutions in, as they are more accurate than using a Bunsen burner because they can be preheated to a set temperature and they are safer and more reliable to use.
• Stop clock ~ to time the intervals for testing the solution and to record the final result, they are accurate and reliable for my needs
• Spotting tiles with a spot of iodine solution in each depression ~ so that the amount of starch in the starch/amylase solution can be tested at set intervals throughout the test
• Glass rod ~ to deliver a small amount of the starch/amylase solution from the beaked to the spotting tile.
• 2 Thermometers ~ to allow me to monitor the temperatures of the starch and amylase as they are heated in the water bath
• measuring cylinders ~ for accurate measuring of the two substances
• beaker ~ to contain the starch and amylase during the testing period.
• 25ml starch
• 5 ml amylase
• Ice ~ to bring the temperature of the solutions down to 0ºc

Safety

Possible risks

Amylase ~ can be harmful to eyes

Solution ~ wear goggles throughout the experiments

Ingestion of substances ~ starch, iodine solution and amylase can be harmful if swallowed.

Solution ~ if any of the above are accidentally ingested, medical attention should be sought immeadiatly.

Water baths ~ water could scould if too hot

Solution ~ make sure water baths are never over heated and use them sensible

Accidents ~ due to immature behaviour

Solution ~ remain focused on my own experiment without distracting others from their work.

Fair test

I am going to make this a fair test by keeping the below variables the same;

1. The volumes of starch and amyalse

How? ~ by measuring them accurately with measuring cylinders on a flat surface.

Why? ~ Because differences in the volumes would affect the amount of molecules of the substances thus affecting the rate

2. The concentrations of both substances

How? ~ By always checking that they are the same that has been used previously.

Why? ~  Differences in concentration will again change the amount of molecule present in the solutions thus affecting the rate.

I am keeping the above the same because this will allow me to concentrate solely on the affects that temperature have on the rate, as if these were to differ it would effect my results.

The one variable that I am going to change will be temperature

Why? ~ because it is the aim of my investigation to find out the effect that temperature has on the rate of the amylase breaking down the starch.

I am trying to prove that the optimum temperature for amylase is 40ºc.

Measurements

I will do my test at these temperatures;

• 0ºc
• Room temperature (20ºc)
• 30ºc
• 40ºc
• 50ºc
• 60ºc

I will have a range of 60 ºc which will allow me investigate my prediction fully.

To make my results more reliable I will repeat the test three times at each temperature and take an average.

Method

• 5ml of starch will be measured and added to a test tube

• 5ml of amylase will be measured and added to a boiling tube

• They will then be heated to the appropriate temperature in water bath if needed, (monitored with separate thermometers).

• The starch and amylase will be combined in a beaker, the stop clock started and a sample immediately taken (by dipping the glass rod in to the mixture an then the spotting tile)

• This process will be repeated every 15seconds until the iodine solution turns a constant light orange/brown colour which indicates maltose (the product of the breakdown of starch)

Obtaining

Results table

I think that my results are reliable as they are quite varied and I tried to take my time when carrying out the tests.  

Graph drawing

I drew a line of best fit on my scatter graph of all my results because it helped to illustrate the decrease in time up to 40 ºc where it peaks and the steady rise passed 40ºc.

This graph shows the rate of the tests, I worked the rate out by dividing 1 by the time taken, this graph is very useful as it illustrates very clearly the peak at 40 ºc that I had predicted and the increase in times towards 0ºc and 60ºc.

There is a pattern in my results that shows that as the temperature increased the speed steadily increased, peaked at 40ºc and then decreased towards 60ºc. the peak at 40ºc agreed with my prediction (the enzyme is designed to work the body which makes its optimum temperature around 40ºc) however I had not expected there to less activity at 0ºc / 60ºc than there was. I think this may be because the extremes of temperatures were not maintained for long enough so

• the solution didn’t get cold enough to actually freeze so the particles maintained there liquid properties meaning that they were still able to move around and collide which enable the reaction to happen.
• The solution was not kept at 60ºc long enough for all the enzymes to be denatured so the remaining ones were still able to break down the starch although in a longer period of time because there were less of them.

Analysing

I feel that apart from the º0c and the 60ºc readings (see above) that my results are good. I know this because I followed the method correctly, and made sure that the amylase and starch were measured accurately with the appropriate measuring cylinders and they agree with my prediction, I also didn’t have any anomalous results  which leads me to believe that they are reliable.

 

Conclusion

From doing this experiment I have proved that the optimum temperature for the breakdown of starch in to maltose by amylase in 40ºc. This is because amylase is designed to work in the body so its ideal environment is that of the body, around 40ºc. Therefore, at this temperature the enzymes can work most efficiently at colliding with and breaking down the starch molecules in their active sites. At lower temperatures the time increased because of the kinetic theory; as the temperature decreases particles loose energy, so collisions are fewer and weaker thus the enzymes take longer to breakdown the starch. At higher temperatures although the particles have more energy the enzymes begin to denature so less are able to function properly so it takes longer for all of the starch to be broken down.

Evaluating

Things that could have affected the accuracy of my results and soloutions;

• Inaccurate measurements of starch / amylase ~ would have affected the amount of particles in the solution thus affecting the rate. (Use the appropriate measuring cylinders, measure on a flat surface and try to use the same equipment for each test)
• Inaccurate timing ~ different people have different reaction times so if different people did the timing on the tests then the results could vary from person to person on then same test. (Have the same person take the time for each test so that the time delay between person and stop clock remains the same throughout)
• Inaccurate interpretation of the colourimeter ~ as I did no have a set colour scale for check the colours with tests could have been ended at the wrong time, too soon or too late. (Design a scale of colours of iodine showing a gradient of concentrations, which can be compared to tests).
• Contaminated equipment ~ if the equipment was not thoroughly cleaned between experiments there could have been a risk of contimination i.e; extra starch or amylase getting in to the test which would have made the measurements inaccurate which would effect the results.( make sure used equipment is washed thoroughly with distilled water and dried before it is used again.

Further work

To further this investigation you could investigate;

• varying concentrations of the amylase and/or starch.
• Vary the volumes of amylase and/or starch

                         

Investigating how temperature affects the enzyme amylase….

Nikki bower 11c1