Denatured Enzymes in Potatoes

  Although 40°c is the optimum temperature we cannot yet say that it is the best temperature as it is the best of the three but it is one temperature out of a range of many. We decided to test a range of five temperatures between 20°c and 60°c, to find the best temperature.

   To improve our experiment we will use a gas syringe to measure the amount of gas given off, instead of an unturned measuring cylinder in a bucket full of water and a bung attached to the end of a tube. This will prevent as much gas release and will leave a smaller chance of anything affecting our final results.

 

 The method, which I used, is reliable and can be counted on to give accurate results. There are no evident random errors, errors that have aroused by fault or any systematic errors, because of fault with the apparatus.
  To improve my experiment, I could have paid more attention in controlling the variables.

   I have confidence in my results because they are close together and constant, also my line of best fit makes a smooth curve through the majority of my results, making them reliable. I think my results were accurate enough for the task and they showed the optimum temperature that catalyses works at, which is 40°C. There was one constant anomalous result in my results, which was for the temperature of 35°C. It was very clear that it was an anomalous result because it lay quite far apart from the other results in the graph. This is most likely to be there because the water baths were at the wrong temperature or the amount of gas in the gas syringe was not read properly.

   The line of best fit on the graph of results shows a positive correlation up to 40°C and then a sudden negative correlation with a steep gradient.

  This is because, as the temperature rises, the activity of the enzyme increases as the atoms within the enzyme begin to vibrate more vigorously, but at 40°C the vibrating atoms begin to knock the enzyme out of shape and it becomes denatured and its active site will no longer combine with the hydrogen peroxide so the volume of oxygen being produced, and rate of enzyme activity decreases and the correlation of the graph comes down. The graph and results suggest that the optimum temperature at which catalyses work is 40°C.

  As the temperature rises, the enzyme activity will increase until the high temperatures denature the enzyme and then the enzyme activity will decrease. The enzymes will denature because when the temperature increases the atoms within the enzyme molecule will begin to vibrate, at first the rate will be low because the enzyme will not be vibrating much so it will not have much energy form the reaction. The more the temperature increases the more the atoms will vibrate which will begin to knock the enzyme out of shape and denature it until the active site of the enzyme, will no longer match up with its specific substrate molecule.

   I think I have enough evidence to draw a conclusion, as the majority of my results are close to the line of best fit, this gives me confidence that my results are accurate and reliable.

   The optimum temperature at which catalyses reacts at the quickest rate is 40°C. As temperature increases during an enzyme catalysed reaction, the enzyme activity rate increases as well until the enzyme reaches its optimum and is denatured by the vibrations of its atoms becoming too vigorous and knocking it out of shape because the temperature rise has caused them to gain more energy. Then, as the temperature rises, the enzyme activity rate drops because the enzyme is no longer the right shape to catalyse the reaction.

Enzymes are biological catalysts. They are proteins and aid metabolism within the body by catalysing metabolic reactions. They speed up reactions without being affected themselves, by the reaction. They take part in anabolic reactions, which build up large molecules from smaller ones, and catabolic reactions, which breakdown larger molecules into smaller ones. The breakdown of hydrogen peroxide by catalyse is an example of catabolism. Enzymes take their action because of their specific shape, much work with only one kind of substrate, such as catalyse with hydrogen peroxide. They work by giving the substrate molecules a surface to stick to where they can collide with other molecules if they need to; this increases the number of collisions and rate of reactions. Enzyme specificness can be explained by the ‘Lock and Key’ hypothesis.

Lock and Key Hypothesis:
   Enzymes are proteins folded into a complex, three-dimensional shape. They have an active site that allows them to act as a catalyst. The active site is a certain shape and only one molecule of substrate, of the same shape will fit into the active site of the enzyme. The molecule of substrate will now react to form a molecule of product, which will leave the active site. The enzyme lowers the energy needed for the reaction, and the reaction is then much more likely to take place.

  In our investigation, the molecule of substrate is hydrogen peroxide, the enzyme is catalyse and the molecules of product are oxygen and water. This hypothesis can be affected by temperature and pH because if the enzyme becomes denatured by either a temperature that is too high, or if the pH is to acidic or alkali and the active site becomes the wrong shape for the specific substrate molecule to fit. Enzymes can be used over and over again though as long as they do not become denatured.

Particle Theory:   The Particle Theory states that the rate of reaction depends on how often and how hard the reacting particles collide with each other. That the particles have to collide with each other to react, and they have to collide hard enough. So more collisions increases the rate of reaction

   This is relevant for the temperature affecting the activity of an enzyme because when the temperature is increased the particles all move quicker. If they’re moving quicker, they’re going to have more collisions. For this investigation it means that when the temperature is increased the hydrogen peroxide molecules and the catalyse molecules move quicker, so there will be more collisions of the hydrogen peroxide with the active site of the catalyse, increasing the rate of reaction, until the catalyse becomes denatured.

  This is relevant for the surface area affecting the activity of an enzyme because if one of the reactants is a solid, in this investigation, the potato, which is the source of catalyse, breaking it up into smaller pieces, will increase its surface. This means the particles around it in the solution, hydrogen peroxide, will have more area to work on so there’ll be more collisions between the two particles.