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Anaerobic Respiration In Yeast

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Anaerobic Respiration In Yeast Christopher Finch Christopher Finch Anaerobic Respiration In Yeast Aim: I am going to investigate how changing the concentration of glucose affects the affectivity of the enzymes in yeast. I will be measuring the amounts of carbon dioxide expelled in the space of 4 minutes. Prediction: I predict that the enzymes in the yeast would react faster as the temperature increases up until a certain temperature, which would cause the enzymes to denature. This is mainly because if the temperature of an enzyme rises to or past a certain amount the tertiary structure of the protein is affected. The molecules begin to clump together and therefore can no longer effectively control the speed of a reaction. This de nurturing usually occurs at a temperature above 45 degrees Celsius as with proteins. I also predict that the concentration of the solution (glucose) would also affect the reaction speed. Using a concentration of glucose, which is too high, would induce plasmolysis to occur. Which would stop the reaction completely. This occurs when (in the case of this experiment) the glucose solution is so highly concentrated that there is more water present in the cytoplasm of the yeast cells than there is in the glucose solution. Osmosis then takes place, the water passes out of the cell into the glucose solution causing the cell to crenelate and so it becomes plasmolysed. ...read more.


There will not be enough available time for this variation of the method to be carried out. Results: 1st Set of results Glucose concentration 1st minute 2nd minute 3rd minute 4th minute 1% 3 2 3 6 2% 3 3 4 5 3% 5 4 4 3 4% 9 0 0 0 5% 6 5 6 10 6% 6 7 13 11 7% 12 15 17 18 8% 5 9 15 8 9% 4 9 12 12 10% 3 6 8 3 2nd Set of results Glucose concentration 1st minute 2nd minute 3rd minute 4th minute 1% 2 3 5 5 2% 3 2 5 4 3% 4 6 4 5 4% 5 4 6 6 5% 6 5 5 4 6% 7 8 7 13 7% 11 16 15 19 8% 6 6 4 8 9% 4 5 5 0 10% 2 0 3 1 Control: * The control is needed so that the reaction between water, which should not make the yeast react, and boiled yeast which, should prove that above a certain temperature the yeast will de-nature. Solution 1st minute 2nd minute 3rd minute 4th minute Water 3 2 1 2 Optimum Glucose Solution (7%) + Boiled Yeast 0 0 0 0 Averages: Glucose concentration 1st minute 2nd minute 3rd minute 4th minute 1% 2.5 2.5 4 5.5 2% 3 2.5 4.5 4.5 3% 4.5 5 4 4 4% 7 2 3 3 5% 6 5 5.5 7 6% 6.5 7.5 10 12 7% 11.5 15.5 16 18.5 ...read more.


As predicted no bubbles of any kind were expelled. Evaluation: The results are quite accurate, as two different sets of methods have been used to compare both. There were slight changes such as the temperature of the glucose, but these were only very minuet. The results found using my second method where different to that found using the first method. This may have been due to small variables; if I were to repeat the experiment I would try and eliminate all of the variables. The results I gained all seem to back up my conclusion and prediction. The results show that increasing the concentration of the glucose would cause plasmolysis to occur and so slow of even stop the reaction. The odd result where no reaction took place proved that the yeast would de-nature at higher temperatures. If I were to do the experiment again I would also use a gas syringe so as to be able to accurately measure the carbon dioxide given off instead of counting bubbles which could have been different sizes so counting the bubbles is not an accurate way to measure carbon dioxide being given off. I would also make use of catalysts, which speed up or slow down the reaction, as a catalyst often provides a surface where particles can meet to react, reactions on these surfaces use less energy so they often allow reactions to work at lower temperate saving fuels. It would also be better for my averages if I were to repeat the experiments more times to be able to find more accurate averages. ...read more.

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