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An investigation into the factors that affect the amount of phosphate produced in the reaction between phenolphthalein phosphate and phosphatase enzyme.

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Biology science investigation: an investigation into the factors that affect the amount of phosphate produced in the reaction between phenolphthalein phosphate and phosphatase enzyme Plan For this investigation I will be investigating the factors that affect the amount of phosphate produced in a reaction between phenolphthalein phosphate and phosphatase enzyme. For this I will obviously need the substances for the reaction to take place. I will take the enzyme phosphatase from the tips of mung bean seeds and add them to a phenolphthalein phosphate substrate. This reaction will produce phenolphthalein and phosphate, when the reaction has stopped the phenolphthalein will turn magenta on addition of an alkali. I can measure the strength of the solution by the darkness of the magenta. I will use magenta filters which will help me determine the strength of the solution, by judging the shade of magenta. I will record the readings I take from using the magenta filters. Method For this investigation I will be using the following apparatus: * Microfuge tubes * Buffer solutions * Phenolphthalein phosphate (substrate) * 10% sodium carbonate solution * 1mm syringes * Mung beans * Pipette tips * Sheets of polystyrene (keep tubes afloat in water bath) * Stop clock * Centrifuge (extract enzyme) * Magenta filters (accuracy: +/- 0.05 units) * Distilled water * Microfuge rack * Waterbath For this investigation I will be using the following method: * Firstly I will place the tips of 2 mung beans in a microfuge tube and using a plastic rod crush them well. ...read more.


Heat supplies the reacting molecules with kinetic energy causing them to move faster. This means the chances of molecular collision are increased at higher temperatures, so it is more likely that enzyme substrate complexes will be formed. However, heat energy also increases the vibrations of the atoms which make up enzyme molecules. If these vibrations become too violent, chemical bonds in the enzyme break and the precise structure, essential for enzyme activity, is lost. Therefore at high temperatures enzymes become denatured. The 'Lock and key' theory is all about how an enzyme is precisely structured with a 'lock' in which a substrate (the 'key') can attach and bond. And so if the lock is damaged and misshapen the key can no longer fit and bond and will not form an enzyme substrate. This I what I expect to happen at the higher temperatures I am using. The lock refers to the enzymes "active site" The active site of an enzyme is the region that binds the substrate and contributes the amino acid residues that directly participate in the making and breaking of chemical bonds. The amino acid residues are called the catalytic groups. Enzymes differ widely in structure, function & mode of catalysis so active sites vary, but possible to make some generalizations. Before I carried out my real experiment I did some preliminary work to familiarise myself with all the apparatus and the method. I got these results: Temperature (�C) Number of magenta units (+or- 0.05 magenta units) ...read more.


I don't think there were any real anomalies in the experiment, although my original preliminary results were certainly anomalous, and I but that down to a lack of enzyme solution in the reaction. The suitability of the procedure was good, I don't think that with the apparatus and time allowed I could have obtained much better results. The only possible thing that could have been improved was when the enzyme solution was being added to all the tubes individually before they were put in the water bath. The time taken for each tube to be filled and closed ranged, so that 1 pf the reactions would have already started whilst all the other tubes were being filled, this could have caused inaccuracy as each tube had a slightly different amount of time in the water bath. Possibly a multiple syringe so that all the tubes could be filled at the same time would help this problem. I think the evidence is reliable enough and sufficient to support my conclusion. I think that my repeat results were a reasonable amount of time from my first results, had they been too far away the results could have been affected. I think that to further this investigation I could record reactions which happen at 5�C rather than at 10�C intervals. This would mean I could find exactly what the optimum temperature is and also at what temperature exactly the enzymes denature. I could also do this investigation using a different variable, such as pH. I could then see how this affected the action of the enzyme. Duncan Howells ...read more.

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