Extracts from this document...

Introduction

The Effect of Concentration on Pectinase Using Apple Hypothesis: As the concentration of pectinase added to apple pulp increases, the faster the rate at which apple juice is produced. Introduction: Enzymes are proteins that speed up and control certain reactions. They work by the substrate molecule binding with the enzyme to form an enzyme-substrate complex. Each enzyme molecule has an active site, where the substrate molecules become attached. The tertiary structure of the protein gives a certain shape to the enzyme and active site and therefore means that only certain shape substrate molecules will fit. This explains the specificity of enzymes. Pectinases are a group of enzymes that specifically target pectins, which are polysaccharides that are found in plant cell wall structure. If the shape of pectinase was like this: The shape of pectin would be like this: This is a section of pectin showing that it is a polymer made up of several galacturonic acid molecules. Galacturonic acid is very similar to glucose, except one of the carbons has a -COOH group attached to it. The pectin chain is held together by a bond between carbon 1 of one galacturonic acid and carbon 4 of the next one and so on. Pectinases are a group of enzymes that specifically target pectins, which are polysaccharides that are found in plant cell wall structure. Pectinases are obtained commercially from species of fungi such as Aspergillus Sp. and Penicillium. The biggest industrial use of pectinases is in the extraction and clarification of fruit juices. Other uses include softening vegetables and extracting agar jelly from seaweed. Pectinase is added to crushed fruit such as apples and grapes to increase the yield of juice extracted from them. Pectinase is an enzyme and therefore its performance is affected by factors such as temperature, inhibitors and concentration - the factor I have chosen to investigate. Pectinase has an optimum temperature of 35�C and an optimum pH of 5.5. ...read more.

Middle

Volume Produced (ml) 0 0.0 0.0 0.0 0.0 0.0 0.0 30 1.1 0.9 1.0 0.8 0.4 0.2 60 1.6 1.3 1.3 1.0 0.6 0.4 90 2.3 1.8 1.6 1.2 0.9 0.6 120 2.6 2.2 1.9 1.5 1.2 0.8 150 3.1 2.5 2.3 1.6 1.4 1.0 180 3.8 2.7 2.5 1.7 1.5 1.0 210 4.2 3.0 2.7 2.0 1.7 1.1 240 4.4 3.3 3.0 2.2 1.8 1.1 270 4.6 3.6 3.2 2.4 2.0 1.2 300 4.7 3.8 3.3 2.5 2.0 1.2 Having done the experiment and looked at the results obtained, it was noticed that after 5 minutes there was still some unfiltered juice left in the funnel. In order to find out the volume of all the juice produced by the apple pulp, a will be used to suck out all of the remaining juice and the final volume of the juice will be noted. This piece of apparatus was chosen to finish off the experiment, as there is only a limited amount of time in which to complete the experiment and this will avoid waiting until all the juice has filtered through. This final volume will not be needed in order to calculate the initial rate of reaction, but is worth recording in order to see how much juice the apple produces and if the method is successful in producing apple juice. Detailed Method: First of all, one 'Bramley' apple is carefully peeled using a potato peeler and the core is removed. It is then carefully chopped up into small pieces using a knife and a tile. The small pieces of apple are placed into a food processor and mixed for exactly ten seconds on the lowest speed. The contents are then put into a mortar and ground up using a pestle. This is done until an apple pulp is produced. The apple pulp is then poured onto a filter paper with a funnel and beaker. ...read more.

Conclusion

One reason why some of the individual recordings may be slightly high is because of the excess juice that filtered out quickly as soon as the test tube was emptied into onto the filter paper. Another reason could be that the time at which the stopwatch was started meant that it was more than 30 seconds of juice obtained. The stopwatch was started after all the contents of the test tube were emptied, which took a few seconds and during this time juice was filtering through. Therefore an improvement to this part of the method would be to find a way of emptying the test tube in one go. Using a slightly bigger test tube or even a boiling tube could do this. The higher than expected values for the rate of reaction could also try and be rectified by increasing the length of time that measurements were taken. This would have provided more data and therefore the graphs and rate of reaction would be more accurate. However this could only be done with more time in which to carry out the experiment. A more general improvement to the experiment would be the precision of the apparatus used. Although the apparatus used was the most accurate available, a more accurate water bath could have been used and also a clearer and more accurate measuring cylinder. Further work to do with this investigation and exploring other factors relating to this experiment can also be carried out in order to add weight to the conclusions made earlier. It is possible to go on and look at the effect of temperature on pectinase and also substrate concentration, however the latter would be fairly difficult to measure. An investigation to look at the effect of pectinase on other fruits such as plums or grapes or investigate changes in concentration of other enzymes such amylase or catalase. These investigations would extend the enquiry of the enzyme pectinase and also into the substrate it is having an effect on. Neal Desai Biology Coursework Mr.Cooksey L62 ...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.