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Investigation to show the effect of temperature on the action of protease on photographic film.

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Investigation to show the effect of temperature on the action of protease on photographic film Aim: to show the effect of temperature on the action of protease on photographic film Prediction: I predict that as the temperature of the enzyme increases, so will the rate of reaction. However, I only predict this until a certain temperature and beyond perhaps 60(optimum temperature) the enzyme will stop working as well and both the enzyme and the substrate will become slightly deformed. As the temperature rises, molecules move much faster and as a result have more energy. This means that they will be more likely to collide so overall increasing the temperature will increase the chances of successful collisions. However with enzymes at the temperature of perhaps 70-75 degrees, their protein structure will break down and their shape may become slightly deformed. This means that they won't be able to fit into the substrate anymore, slowing down the reaction and eventually stopping it. Preliminary experiment In order to familiarise myself with the experiment, I did some preliminary work. I carried out the exact same experiment that I am hoping to do for my final experiment. I measured up 10cm3 of protease enzyme using a syringe (an accurate form of measurement) and placed it in a test tube. I then placed this in a water bath of the required temperature for 3 minutes before placing in the photographic film, to bring it up to the necessary temperature. ...read more.


This is because, as the temperature increases, the amount of energy increases causing the molecules to vibrate and move around more, therefore increasing the number of successful collisions between the substrate and the enzyme. However, this only happens to a certain extent, as after the enzyme reaches its optimum temperature, it will slowly change shape and become denatured. The shape of an enzyme molecule is very important, as it has to fit its substrate exactly. When the temperature increases above 60 degrees, the shape of the enzyme changes and no longer fits into its substrate. This is one of the many reasons that organisms can be killed if exposed to high temperatures for a long period of time. The enzymes in their bodies become denatured and the daily chemical reactions that would usually take place at a faster rate become very slow and the successful maintenance of life stops. Ph Most enzymes work best at a certain ph. Other alkaline or acidic conditions may alter the chemical properties of enzymes. For example, the protein digesting enzyme in the body works best at an acidity of ph 2. However, at this ph, amylase (the enzyme from saliva) cannot work at all. Most enzymes work best in neutral conditions. The ph at which an enzyme works best is known as its optimum ph. ...read more.


It was not easy to judge the end point, at which the film went clear, but once it was taken out I compared it to another piece of photographic film, which had gone transparent, to make sure this had too. In order to improve this, I could somehow have use an electronic device to measure the exact amount of light entering the piece of film, to check its actual transparency. However, it would be very difficult to come across this time of equipment in a school. In order to extend the experiment further, I could carry out a similar experiment investigating the effect of temperature of the action of a different protease, say pepsin on a photographic film. This is because; I could then compare the effect of a bacterial enzyme against a human one. I could also use a wider range of temperatures, to add detail and to be able to draw a more accurate graph based on the results. In addition I could investigate more temperature around the optimum temperature, to find the exact temperature at which the enzyme is most efficient. In order to make the results more reliable I could also do more repeats, or do repeats in separate test tubes, unlike the experiment that I carried out. Both repeats were in the same test tube, which means they could be classed as not repeats, however If I were to carry out repeats in two different test tubes, I would get similar results anyway. ...read more.

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