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Comparing the denaturation rate of fungal and bacterial amylase.

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Comparing the denaturation rate of fungal and bacterial amylase. Plan Amylases are widespread enzymes which hydrolyse starch to maltose. They are often found in two forms, ? amylase which degrades starch molecules into fragments 10 glucose residues long and ? amylase which breaks down these into maltose made up of two glucose molecules. Both work by hydrolysis adding one molecule of water across the glycosidic link. Hypothesis: My hypothesis is that bacterial amylase will work more efficiently at higher temperatures than fungal amylase. Both bacteria and fungi use amylases in their basic method of feeding. Bacteria are prokaryotes which means they are very small and have no true nucleus. They are unicellular but occur together in vast numbers as large groups or entirely separate cells. Being found almost everywhere in air, soil, water and in living things they are of great ecological and economic importance. Many bacteria cause decay and with fungi, facilitate the recycling of nutrients. Bacteria can grow well in a wide variety of conditions and whilst temperatures of 25-45�C are most favourable there is a very wide range with some able to continue to grow slowly near to 0�C and others able to survive hot springs above 80�C. On the other hand fungi are eukaryotes which means they generally have larger cells and have membrane bound organelles. Fungi comprise the moulds, yeasts, mildews, mushrooms, puffballs and rusts. They can be saprophytic, feeding on dead organic matter or parasitic. Fungi consist of a fungal body, the mycelium which is made up of fine threads called hyphae. In a specialised part of the mycelium, spores are produced in vast numbers and dispersed. Moulds which are multicellular fungi, grow best at temperatures of about 30�C, their growth is slowed at lower temperatures. In trying to rid foods of moulds the food is heat treated at 60-70�C. In comparison bacteria are heat treated to 100�C or more before they are killed off. ...read more.


1 180 2 210 3 150 Mean 180 Fungal amylase Test number Time taken for iodine colour change (s) 1 30 2 30 3 30 Mean 30 To enable me to compare the effects of temperature treatment on each enzyme I calculated the overall rate of reaction for each using the formula: I then expressed the rate of each reaction as a percentage of the rate of the untreated enzyme. The results are shown in the following summary table: Conclusions Main trends and patterns The results show that there is a significant difference in the response of bacterial and fungal amylase to different temperature treatments. The raw data shows that bacterial amylase is significantly less active in these conditions compared with fungal amylase. Fungal amylase retains 100% of its activity when treated at temperatures up to 60�C. Above this temperature fungal amylase activity rapidly decreases to less than 5% of its original rate but still retains some limited activity even at when treated at 90�C. Length of time of treatment appeared to have little effect on this pattern since there were only small variations at 70�C and at 90�C. In contrast bacterial amylase activity was inhibited by treatment at 40�C for 600s and 900s. It could be said therefore that the bacterial amylase was more sensitive to temperature but although activity was inhibited the bacterial enzyme was affected much less by treatments in the range 50-90�C. It can be seen from the graph that the bacterial enzyme retained over 50% of its activity up to 80�C. It also appeared that length of time of treatment was also more important to the activity of bacterial amylase as there was an obvious relationship showing that the longer the treatment the slower the reaction at three of the temperatures tested. The results for bacterial amylase also showed a much greater degree of variability. There were obvious anomalies at 60 and 80�C for the 900s treatment although it was interesting to note that all of the rates rose unexpectedly between 50 a n d 60�C. ...read more.


There is good evidence from the conclusions and the separate limitations section that the candidate is well aware of the major limitations and anomalies in this investigation: The cautious nature of the final conclusion and the analysis of the shortcomings of the experimental technique show an awareness of the tentative nature of the results obtained. Whilst this is rather short it does identify all the important points and is close to a maximum 8 marks The candidate recognises that the variability of the bacterial amylase results in particular needs further investigation and the suggestions for further study in carrying out more repeats, investigating the important temperature range in more detail and looking at a wider range of enzymes from bacteria and fungi are well chosen. and clearly closely related to the hypothesis under investigation. Once again this would benefit from a little more discussion in depth but it is refreshing to see important points selected and commented on with some conciseness rather than being hidden in long accounts of sometimes irrelevant background theory. This again is a good concise summary which meets the criteria for 8 marks well. 8 marks were awarded for analysing evidence and drawing conclusions. TOTAL Planning = 8 Implementing = 7 Analysing = 8 Evaluating = 8 Overall total: 31/32 Context of this investigation Following theoretical work on enzymes, the group of students performed simple laboratory experiments on amylases and proteases recapping their Key Stage 4 work on peroxidase. They were provided with samples of different enzymes and asked to investigate some basic properties in detail. Several students investigated temperature effects but initial planning and pilot tests were individual and this resulted in very different approaches to the problems of heat treatment, assessing end points and numerical analysis of data which were clearly reflected in the final reports. In awarding the highest mark the centre was therefore confident that this was the individual work of a very able student. The candidate spent approximately three hours on the practical work. ...read more.

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