I used the concentration of 6ml3 of which 2ml3 was amylase and 4ml3 was starch. This gave me enough solution to fill 3 dropping tiles with 3 drops of the solution into each well.
I used the same iodine for each experiment as some times they differ.
I used 1% in the case of the amylase and the starch, instead of 0.1%.
The equipment that I used was:
- Water baths that reach a temperature of 70 C
- Pyrex test tubes
- Syringes
- 3 dropping tiles
- Iodine
- A dropper
- A stop watch
- Two thermometers
I measured out 2ml3 of 1% amylase solution by syringe and emptied it into a Pyrex test tube. I then measured out 4ml3 of 1% of starch solution by syringe and emptied it into a different Pyrex test tube.
I then got two thermometers, one in each test tube. I then placed each test tube into the water bath of the chosen temperature. When both solutions had reached the temperature of the water bath, I mixed them and started the timer. At every 10-second interval I took 3 drops of the solution in a dropper and mixed it with 3 drops of iodine in one of the wells in a dropping tile.
I did this until I had filled up 3 dropping tiles of until it was obvious that the iodine had returned to its original colour.
I counted the wells in which the colour was different to the colour of the iodine and also the last tile. I then multiplied that number by 10 therefore giving me the number of seconds taken for the amylase to brake down the starch.
I wore safety goggles and an overall for safety reasons.
I predict that the rate at which the starch will be broken down will increase as the temperature rises from 10C to 50C. Then the rate at which the starch is broken down will decrease at every 10C interval until it will no longer be noticeably broken down within 360 seconds which is the equivalent of three dropping tiles. This will occur at about 70C-80C.
Enzymes are large protein molecules, which are catalysts. They are essential to the body to speed up chemical reactions in the body. Without them you would die as the chemical reactions would occur, but would be to slow to keep you body functioning properly.
Enzymes speed up this reaction by diverting, and therefore lowering, the activation energy of the chemical reactions.
The enzyme called amylase brakes down the substrate called starch. Starch is broken down in to maltose.
Amylase does this by the active site of the amylase locking on to the substrate, starch, as they are made to fit perfectly. When they connect, the amylase brakes down the starch molecules. Therefore, the more frequent the amylase molecules collide with the starch molecules the quicker the reaction takes place, so the quicker the starch is broken down This is called the lock and key theory.
For the starch and amylase molecules to collide more frequently they must gain energy to move faster. The energy gained is supplied by heat. Heat energy is transferred to the starch and the amylase molecules; this is then converted into kinetic energy. That is why I predict that the higher the temperature is the higher the rate of reaction will be.
I have also predicted that at 50 C the rate of reaction will start to decrease. I predicted this because I know that the enzyme amylase has an optimum temperature of roughly 50 C. Above 50 C the amylase molecules will start to denature, this is when the heat starts to change the shape of there active site, therefore making connection between the amylase and the starch molecules, which are denatured, impossible. Therefore only the unchanged molecules can connect with the starch molecules and successfully break them down. This takes longer as many amylase molecules are useless. When the temperature is as high as 70 C-80 C there are not enough amylase molecules left, that are still in tact, to get any noticeable breakdown of starch within about 360 seconds.
I predict that the rate of reaction will be doubled for every 10 C rise in temperature. This is called the Q10 theory. This will be shown by the gradient of the graph, which should be equal to two. This will only be relevant until over 50 C where the change will occur.
When I plotted my results on a graph (as shown below), I drew a line of best fit. On my graph the line of best fit was straight and slanted down until 50 C then it slanted up as a straight line to 60 C.
On the second part of the line I have continued plotting the line as a dotted line down with a ruler carrying on the line to zero on the y-axes. When the line reached zero on the y-axes it was exactly on 40 C. This proves that my results were accurate from 50 C upwards.
To find the rate of reaction I had to find the gradient of the line of best fit. I have done this for the first part of the graph and have shown this on the first part of the graph.
This is how I did it:
Gradient= y
x
Gradient= 20
10
Gradient= 2
This proves my prediction correct.
Enzymes are large protein molecules, which are catalysts. They are essential to the body to speed up chemical reactions in the body. Without them you would die as the chemical reactions would occur, but would be to slow to keep you body functioning properly.
Enzymes speed up this reaction by diverting, and therefore lowering, the activation energy of the chemical reactions.
The enzyme called amylase brakes down the substrate called starch. Starch is broken down in to maltose.
Amylase does this by the active site of the amylase locking on to the substrate, starch, as they are made to fit perfectly. When they connect, the amylase brakes down the starch molecules. Therefore, the more frequent the amylase molecules collide with the starch molecules the quicker the reaction takes place, so the quicker the starch is broken down This is called the lock and key theory.
For the starch and amylase molecules to collide more frequently they must gain energy to move faster. The energy gained is supplied by heat. Heat energy is transferred to the starch and the amylase molecules; this is then converted into kinetic energy. That is why I predicted that the higher the temperature is the higher the rate of reaction will be. This was proven.
I have also predicted that at 50 C the rate of reaction will start to decrease. This was also the case. I predicted this because I know that the enzyme amylase has an optimum temperature of roughly 50 C. Above 50 C the amylase molecules will start to denature, this is when the heat starts to change the shape of there active site, therefore making connection between the amylase and the starch molecules, which are denatured, impossible. Therefore only the unchanged molecules can connect with the starch molecules and successfully break them down. This takes longer as many amylase molecules are useless. When the temperature is as high as 70 C-80 C there are not enough amylase molecules left, that are still in tact, to get any noticeable breakdown of starch within about 360 seconds.
I predicted that the rate of reaction would be doubled for every 10 C rise in temperature. This is called the Q10 theory. This will be shown by the gradient of the graph, which should be equal to two. This will only be relevant until over 50 C where the change will occur.
As this has happened my prediction was correct.
Most of my results are perfect. However there is one result that is a bit off compared to the other results. This is the result for 20 C. This maybe because in all the other experiments I used a thermostatic water bath but as room temperature is roughly 20 C I did not use a water bath. This could have affected my result for 20 C as it may have been a few degrees below and the thermometers could have been slightly wrong. It could also be because I miss read the colour change of the iodine. It could also have been caused by the fact that I did the set of results last, on a different day to my other experiments when the weather may have been colder therefore bringing down the room temperature I may have miss read on the thermometers.
I could have taken more results for each temperature. I could have taken results on a wider range of temperatures I could have used the same thermometers each time to make my results better.
