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Investigation in to the effect of temperature on a cell membrane.

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Introduction

Lab Report 1) Title Investigation in to the effect of temperature on a cell membrane. 2) a) Hypothesis The change in temperature will have an effect on the cell membrane. b) Null Hypothesis The change in temperature will have no effect on the cell membrane c) Prediction The increase of temperature will have an effect on the cell membrane. I think the higher the temperature the more pigment will be released from the cell vacuole, showing that the cell membrane is damaged. I also think the pigment must stay inside the cell when it is healthy as it is water-soluble and therefore may only move through the membrane by facilitated diffusion. I know temperature does have an effect on many of the components that make up the cell membrane. Firstly the cell membrane has many proteins, many passing all the way through the membrane. I know that proteins are made up of amino acids held together by peptide bonds. Also to form the protein tertiary structure the proteins has other bonds such as hydrogen, disulphide and ionic. When the temperature rises these bonds break causing the proteins to denature. They will then create holes in the membrane allowing the pigment to diffuse at a faster speed. ...read more.

Middle

These results also show that there was a massive increase between 60� and 70� suggesting that something considerable happened between these temperatures. Also the fact that the temperature had no effect on the membrane till approximately 45� is also significant. I have also worked out the correlation coefficient of my graph and found it to be 0.8. This showing at quite strong positive correlation showing that my results follow a general trend. 7) Explanation These results can be explained. I think the reason that there was no change in the membrane till approximately 45� is because at this temperature there is no effect on the components of the cell. Then at 45� we see a slight increase in the amount pigment released and this steadily increases till about 65�. I think the reason for this increase is the beginning of the breakdown of the lipids, creating little holes in the membrane. Then at 65� we see a massive increase in the amount of pigment released. At this point I think it is the protein denaturing causing bigger holes in the membrane allowing the pigment to flow freely through the membrane. I also have to consider that somewhere the fluidity of the membrane would cause holes in the membrane but looking at my graph it is hard to say where this occurs. ...read more.

Conclusion

During the experiment I had my beetroot in an empty beaker. By leaving them in the open air the discs may have become dehydrated meaning when placed into the water the water will first have to enter the cell by osmosis because the water potential inside the cell may be lower than that of the surroundings, this must happen first before the pigments can start to diffuse out, so for some of the time the beetroot is immersed in the water it is re-hydrating. Of course this means the beetroot that was left out the longest will have been the most dehydrated, therefore it would not start to diffuse for a longer time. The modification I would have made then was keeping the beetroot immersed in water during the experiment. Then there was the limitation of keeping the water bath at a constant temperature with just a Bunsen burner and the use of cold water. I don't think this would have been a major limitation because as long as the temperature was keep within in a degree or two no major difference would be found, but if it was raised or lowered it could have stopped or started to effect the membrane when not wanted. But a good modification would be the use of an electronic water bath. Aimee Kelly Page 1 07/05/2007 ...read more.

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