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An investigation in to the effect of temperature on the release of pigment from beetroot tissue

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Introduction

An investigation in to the effect of temperature on the release of pigment from beetroot tissue Introduction and Hypothesis I think that the increase of the temperature on the beetroot will affect the diffusion of the colour dye in the beetroot. The colour dye is held together by the membrane structure and this maintains the red rich colour in the beetroot. I believe that with the increase of temperature applied onto the plasma membrane, the structure of the membrane will become damaged and the membranes of the protein will eventually denature. Scientists know that cell membrane have the following general characteristics: - * 40% Lipid * 0 - 10% carbohydrate (as prosthetic groups) * 50 - 60% protein. You can see from above that proteins are major constituents of membranes. In membranes there are intrinsic and extrinsic proteins. Intrinsic membrane proteins pass through the lipid layers. They have a variety of functions; one of them is assisting the transportation of molecules through the membrane. These proteins have both an extra and intracellular part. Extrinsic membrane proteins are embedded in the outer layer. They can often act as chemical receptors for the cells. The majority of the proteins in the membranes are globular. This will mean that the 3 dimensional shape of the structured protein held together by the hydrogen bonds can eventually be broken if high enough temperatures are applied onto them - this is called denaturisation of proteins. I am working specifically on beetroot, it is known that proteins in plants are more likely to withstand higher temperatures and therefore denature at a higher temperature. So I would expect for the proteins in beetroot to denature at about around 50 degrees Celsius. Once the proteins are denatured they are no longer able to maintain the precise shape and carry out the functions. This will mean that the denatured proteins can possibly cause holes in the membranes. ...read more.

Middle

I will time the test tubes to be in the water baths for the beetroot pieces to submerge in for 5 minutes. I feel 5 minutes is valid enough for sufficient diffusion to occur. And that if any more time is given, especially with the higher temperature ranges (i.e. 90) could possibly exceed the colorimeter readings due to the possible high intensity of light absorption. I will use a stop clock to time the 5 minutes. After performing the tests of a particular temperature range, I will use a colorimeter to measure the amount of light absorption obtained from test fluids of each test (liquid substance in the test tube). To measure the amount of red pigment that has been released out of the cells and onto the water, I will need to use a colorimeter. I will actually not be directly testing the amount of release of red pigment; I will really be testing the amount of light absorption obtained through the test fluids. I will actually need to produce a blank standard where water is placed into a curette as a control. I will first put the 'blank' standard curette inside the colorimeter. It should set the colorimeter at '0' light absorption. This will ensure that the colorimeter machine functioning correctly. After finishing the control test, I will start measuring the amount of light absorption from the real test fluids. I will have to follow the same procedure as I had done with my blank standard control test, except of course that I will be expecting the readings of my real test fluids to be more than '0' light absorption as they will be real test fluids. I will have to follow exactly the same procedure for all of my 'to be' 15 test fluids. I will of course note my results (the readings of the light absorption) from each test fluid. ...read more.

Conclusion

It was of the same size, although not exactly of the same weight, the same amount of surface area did come into contact with the same amount of water and at the same amount of time given. Although I did not weigh the pieces to ensure that the mass were the same, the beetroot pieces were all cut using the same way - through cutting sideways of the beetroot to obtain uniform cylinders- it was likely to have the same composition of cells. Though it was possible, altough rare that they would be exceptions, hence causing anomalous results. If I was to repeat the experiment again and start to consider weighing the pieces, I would have to use specialised weighing equipment. There would also be the problem of what to do if the pieces' weights did not match one another - could it be that I would have to cut a bit of the piece, hence making the surface area contact with the water to later be different and unfair during the tests. If I were to make further improvements of the investigation I would have more than one person working in my group for the investigation and would also give my myself more time. I would have also like more water baths so I could have more temperature ranges to work from. This will enable me to analyse more precisely what would have happened between the temperatures that I had done. It could have been that between 60 degrees Celsius and 65 Celsius, the liquification of lipids had actually blocked the route of the release of red pigment a little, and a decrease of light absorption would have been evident. I would have also have liked to perform more than 3 tests - say about 5 at least, with enough colorimeters and 'hands' to make it fair, and would get a very accurate mean of results from. As this would prove that the results obtained are most likely not obtained due to an external factor. ...read more.

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