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An investigation of the enzyme catalysed hydrolysis of urea - To find out how long the urease takes to produce an alkaline solution at a known concentration of urea and urease, and at room temperature.

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Introduction

AN INVESTIGATION OF THE ENZYME - CATALYSED HYDROLYSIS OF UREA AIM: 1. To find out how long the urease takes to produce an alkaline solution at a known concentration of urea and urease, and at room temperature. 2. To use similar substrates urea, ethanamide and methylurea, to test the specificity of the enzyme. 3. To enable you to plan a more extensive investigation of the properties of urease. BACKGROUND INFORMATION: Urease appears as a white powder, which can be found in both plant and animal cells. This powder can be found in certain plant seeds, for example, watermelon or jack beans, it can also be found in the cellular structure in our bodies. Urease is made to use generated urea as a nitrogen source, as this is the enzyme that controls urea decomposition. However it also has many other uses. Another example of its uses can be found in plants. As urease helps in the systemic nitrogen transport pathways, and can also act as a toxic defence protein. Urease in our bodies is only used through excretion purposes, as urea is broken down into two products, ammonia and carbon dioxide. These can easily be excreted through the cell by exocytosis, which then can be removed from the body though mouth, nose, urine, faeces etc. Urease can also be used in industry for many treatments and to test for medical conditions. The reactions happening in this experiment would have happened inside animal and plant cells. In animals, urea is broken down in the gastricmucosa found in the stomach, by the enzyme urease. Urea is broken down into carbon dioxide and ammonia. In plants it is used to help increase the overall efficiency of the plants nitrogen use. This background knowledge explains how important biologically urease is needed, in breaking down urea into simpler substances, which can be excreted easier. It shows how without it, it could lead to problems concerning our future existence. ...read more.

Middle

However, before I add the urease, I would have putted the urease in the specific water bath for several minutes. 3. Add the solution of urea and hydrochloric acid with the indicator and start the stop clock 4. As soon as the solution has turned blue indicating alkaline, this will be done through observation, stop the stopclock. 5. Record the time taken, and the final colour of the indicator. Use the time to calculate the rate of the reaction. 6. Again repeat the method for the temperature three times to allow an average to be taken. The temperature method only needs to be carried out with the substrate urea. Below shows how my results tables will look before any values are entered. Below is the results table showing the specificity of the enzymes. Substrates Final colour of indicator Time taken (seconds) Average time (seconds) Rate of reaction (1/ average time) Urea 1) 2) 3) 1) 2) 3) Methylurea 1) 2) 3) 1) 2) 3) Ethanamide 1) 2) 3) 1) 2) 3) Below is the results table showing the temperature being the variable affecting the enzyme, urease. Temperature of enzymes (�C) Final colour of indicator Time taken (seconds) Average time (seconds) Rate of reaction (1/ average time) 30 1) 2) 3) 1) 2) 3) 40 1) 2) 3) 1) 2) 3) 50 1) 2) 3) 1) 2) 3) 60 1) 2) 3) 1) 2) 3) FAIR TEST: Using the same equipment, pr similar equipment would help in making the experiment fairer, as by using the same equipment, the measurement would all be totally accurate. I would also try to prevent the contamination of the urea and urease jars, and acid jars. This also includes using the right pipettes for each solution. I will also make sure I do the experiment on my own, as this better, as I would stop and start the stop-clock, according to when my eyes see the right time or the right reading. ...read more.

Conclusion

I have circled an anomaly on graph 3 and 4, which had occurred when I was investigating the rate of reaction of the enzyme at 40�C. This anomaly may have occurred due to the water bath not keeping at 40�C. During my experiment I tested the water baths to see if they all were at the right temperatures, I found they were not. I could do nothing about this, as other people experiment would have been unfair if I changed the temperature. Therefore, as a solution I would keep all temperatures at the right temperatures before I start the experiment. I would do this if I were doing the experiment again by myself so other peoples experiments could not be disturbed. There were also other factors affecting the results, which mainly involved human error. People working in my group may have failed to start and stop the stop clock at the right times. Other member of the class may have contaminated different solutions with each other, I was careful and avoided this but other people may have not been. People in my group forgot to leave the two solutions in some water to acclimatise, so each solution starts off with the same temperature. If this experiment was done extremely accurately, with many-repeated experiment creating a more accurate average, then a reading may have been made for ethanamide. Avoiding these factors and improving certain parts of the apparatus and experiment would have achieved then better results. Apparatus like the water baths caused the experiment to be unfair, as they were not constant at their specific temperatures. Above all I believe this experiment went well, as I had fulfilled my objectives and collected a group of accurate data. If I wanted to investigate the activity of enzymes further I could have used other variable, which would affect the enzymes and rate of reaction. Other variable that I could use could be, varying the pH levels and concentration of the solutions or using different amounts of a particular solution. ...read more.

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