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Enzymes at work

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Enzymes at work The aim of my investigation is to find out what pH the enzyme named peroxidase works best at. We can find the enzyme peroxidase if we grind up celery, or most other animal and plants. A chemical reaction in plants and animals produce hydrogen peroxide, this can poison them if it is allowed to accumulate. The enzyme peroxidase acts as a catalyst for decomposing hydrogen peroxide, it is broken down into water and oxygen. The reaction is: 2H20 = 2H20 + O2 (Aq) (L) (G) I plan to measure the amount of oxygen given off by the celery at different pHs and whichever pH helps the enzyme produce the most oxygen. Before I do this I must do a preliminary plan to see what my other variables should be so that I can get the best results. I predict that the optimum pH will be around 7 because if it goes any lower or higher than this it could change the enzymes shape and/or charge properties of the substrate so that either the substrate cannot bind to the active site or it cannot undergo catalysis. Different enzymes have different optimum pHs and it is hard to say what it will be because some enzymes work best at low temperatures and others at high temperature. As you can see from the graph the two different enzymes, represented by red and green lines, have a different optimum pH. ...read more.


The optimum time is as long as possible and the optimum amount of potato is as much as you can get but I used 15, in my actual experiment I will use less because it is time consuming to use any more. To make the experiment a fair test I must consider the variables and what I will change and keep the same. The only variable I will continually change throughout the experiment is the pH, I will keep everything else at a set amount and not change it throughout my experiment. I will use my preliminary plan on helping me discover what would be give me the best results. Plan I will use: * Conical flask * Goggles * Gas measuring cylinder * Delivery tube * 500ml beaker * Clamp * Stop watch * 10ml syringe * Solutions * Celery I will: 1. Collect my equipment and safety equipment 2. Fill the beaker with water. Fill the gas cylinder up with water and put it upside down in the beaker making sure not to let any leak out, then hold it in place with a clamp. 3. Crush up some celery (5ml) and place it in a conical flask making sure to measure out the right amount. 4. Extract some peroxidase (5ml) from the flask, making sure to get the right amount and put it in the conical flask. ...read more.


The body will of adapted to suit this and so will the enzyme, this is why the optimum pH is pH 7. The temperature also plays a big role in how the enzyme reacts, for my experiment I kept it at room temperature but for the enzyme to work better it would have to be at the body's temperature. If I was to do this experiment again I think I would try and change the temperature so that it suits the enzyme more. I would also try and get the celery to be the same age because my experiments over two days with two different celeries, which could have had an effect and gave odd results. The odd results could of came from anything though, we could of measured slightly wrong, measured the solutions wrong, or when we did measure the solutions there could have been leftover acid in the syringes. I was able to get sensible results in the end after redoing the tests that had odd results. But overall I successfully carried out my investigation fairly and accurately. My experiment was good because I have measured all my solutions accurate, added the solutions together in the same order, timed my experiment to the best of my ability, I have kept the temperature the same and I have produced an experiment that is fair and accurate. ?? ?? ?? ?? Dean Blewitt 1 ...read more.

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