Extracts from this document...

Introduction

Investigation: The Effects Copper Sulphate has on Catalase. Aim: The aim of this investigation is to find out how Copper Sulphate in a reaction affects the way catalase works, in the same reaction (http://www.ocr.org.uk/). Background: An enzyme is a protein, which can be defined as a biological catalyst. A catalyst is used in chemical reactions, to speed it up, if the reaction is going slowly. The good thing about this is that it does not get used up itself, so you can use the catalyst over and over again. (http://www.biology.demon.co.uk/Biology/mod1/enzymes/enzyme.htm) An enzyme is coiled up into a precise three-dimensional shape with R groups on the outside. These R groups ensure that the enzyme stays soluble. (http://www.enzyme.com/) An enzyme is a very large molecule but only a small part of it is involved in the reaction. This small part is called the active site. In this active site, a specific substrate fits in it, to form an enzyme - substrate complex. (http://www.s-cool.co.uk/topic_index.asp?subject_id=3) When the amino acids have reacted with the substrate, the substrate is released from the active site, but not as a substrate but as products because the substrate has been broken into two halves. The active site is now available for the next reaction. (http://www.bbc.co.uk/asguru) Substrate - in this case the substrate will be the copper sulphate. The active site Substrate (copper sulphate) The Enzyme The Enzyme Active site Substrate into Products The only things that can affect the way the enzymes work are inhibitors. These try to inhibit the active sites. If this happens, then there is a competition between the substrate and the inhibitor, for the active site. If the substrate has more concentration than the inhibitor, then the substrate will successfully bind to the active site, which means that the enzyme will be able to function as normal, without any problems. (http://www.expasy.ch/enzyme) But if the inhibitor has a higher concentration then the substrate, then the substrate will not bind to the active site, which means that this will affect the way the enzyme functions. ...read more.

Middle

As the temperature continues to rise, however, the hydrogen and ionic bonds, which hold the enzyme molecules in shape, are broken. If the molecular structure is disrupted, the enzyme ceases to function as the active site no longer accommodates the substrate. The enzyme is denatured. To control this variable, the temperature was maintained at a fairly constant level that allowed the enzyme to work effectively (room temperature, approximately 23�C). This was achieved by using a test tube rack and tongs to handle the apparatus so that the heat from my hands did not affect the Catalase. * pH: Any change in pH affects the ionic and hydrogen bonding in an enzyme and so alters it shape. Each enzyme has an optimum pH at which its active site best fits the substrate. Variation either side of pH results in denaturation of the enzyme and a slower rate of reaction. In this experiment, the pH was kept constant using a pH 7 buffer, selected to maintain a pH level suited to the enzyme by being equal to the natural environment of the enzyme (potato tissue). * Substrate Concentration: When there is an excess of enzyme molecules, an increase in the substrate concentration, produces a corresponding increase in the rate of reaction. If there are sufficient substrate molecules to occupy all of the enzymes� active sites, the rate of reaction is unaffected by further increases in substrate concentration as the enzymes are unable to break down the greater quantity of substrate. * Inhibition: Inhibitors compete with the substrate for the active sites of the enzyme (competitive inhibitors) or attach them to the enzyme, altering the shape of the active site so that the substrate is unable to occupy it and the enzyme cannot function (non-competitive inhibitors). Inhibitors therefore slow the rate of reaction. * Enzyme cofactors: Cofactors are none protein substances which influence the functioning of enzymes. ...read more.

Conclusion

I did change things from my preliminary, which I have also stated in my method. The one main problem I came across to while I was doing my experiment was that went between the time when I put the solutions into the conical flask and I put the bung on, some gas produced would have escaped, which meant that I did not record all the gas produced. I tried to find a solution to overcome this. I researched this in several textbooks and Internet sites (see reference section at the end of this coursework) but I could not find anything. The equipments that I stated in the method were all used. The equipments were perfect for this experiment especially for collecting the gas produced and measuring out solutions. While I was looking through my results table and finding the averages, I found out that the 0.25m started off slower than the 0m but when it started to produce oxygen, it produced the highest level. This was a surprise to me because at this time, the hydrogen peroxide would have been binding to the active sites more than 0m but not as much as the copper sulphate, which meant that the gas being produced would have reduced and not exceed 0m but it did. But when I calculated the averages, the 0m average was higher than the 0.25m average and not that much. If I had to do this experiment again, the things I would change or improve are as follows: * I would do my experiment with the potato solution and then compare my results with the neat catalase. I know that the potato solution oxidises and turns black when left over night, so I would try to do the experiment in one day. * In this experiment I was using 0m, 0.25m, 0.5m, 0.75m and 1m, if I had to do the experiment again, I would use different types of molars, e.g. 0m, 0.1m, 0.2m, 0.3m, 0.4m, 0.5m, 0.6m, 0.7m, 0.8m, 0.9m and 1m. ...read more.

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.