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Investigating how changing the concentration of sucrose, affects the time it takes for a reaction to take place with Sucrase

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Introduction

Investigating how changing the concentration of sucrose, affects the time it takes for a reaction to take place with Sucrase Aim: To find out how varying concentrations of the substrate (sucrose) affects the rate of reaction with the enzyme sucrase. Hypothesis My hypothesis is that as the sucrose concentration increases, the rate of reaction will also increase. Scientific Knowledge: Enzymes are biological catalysts which increase the rate of a chemical reaction without directly taking part in the reaction. For substrates to be broken down into their The necessary components of a enzyme reaction are an enzyme and a substrate. In the case of my experiment, the substrate is sucrose and the enzyme is Sucrase. During the reaction, sucrase breaks sucrose into its two monosaccharide constituents, glucose and fructose, by catalyzing the hydrolysis reaction in which the bond holding together the subunits is broken down by the addition of Hydrogen and Hydroxide from a water molecule. The enzyme remains unchanged at the end of this reaction. The monosaccharide combination of glucose and fructose are connected together to form sucrose by a 1,4 glycosidic bond. I believe that as the sucrose concentration increases, so will the rate of reaction, but only up to a certain point. ...read more.

Middle

In my experiment no inhibitors were used, and all of the work surface near to the experiment was kept clear of inhibitors to ensure that contamination was not a possibility. - Acidified Potassium Manganate (vii) -I kept the levels of acidified potassium manganate constant throughout the experiment, as if the level of this varied, then the time it takes for it to decolourise would be longer or shorter then is actually the case if the experiment was done more accurately. For this reason, I paid explicit attention to the levels of this. - Equipment - All of the equipment that was used was thoroughly washed so that any possibility of contamination from previous usage was eradicated, and was also dried so that the concentrations were not affected. Apparatus: * water bath - one at 38�C and one at 60�C * test tubes * stop clock * measuring cylinders * acidified potassium manganate (vii) * water * sucrose (In varying concentrations in the percentages: 2, 1.6, 1.2, 0.8, 0.4, 0.0 ) * sucrase (1% concentration) * thermometer * 4 pipettes * Bunsen burner * Tripod * Gauze * Fireproof tile * beaker Method: I will vary the concentration of the sucrose by mixing it with the proportional parts of water, for each test. ...read more.

Conclusion

This would show that my hypothesis was correct. I think that if I had used higher concentrations of sucrose, then I would have discovered that there is a point where the rate of reaction would level off. This is because all of the substrate has been broken down and there is not enough for it to continue reacting. The point at which the curve levels off, and the rate of reaction remains constant no matter what the concentration of the substrate is known as Vmax. Evaluation: I believe my experiment was a success which proved my hypothesis. I think that if I were to repeat this experiment, there would be a number of things which I would change. Firstly, I would work with a much larger variable, so my concentrations would be much higher, maybe even working up to 100% sucrose concentration, so that the exact point of Vmax could be found for the enzyme concentration that I am working with. Also, I would change some different variables, to see how this would affect the experiment. I would change the enzyme concentration, and try and look at the Vmax for a small number of different enzyme concentrations, and also I would change the temperature to see how this affects my results. TEJINDER NIRWAL BIOLOGY COURSEWORK ...read more.

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Here's what a teacher thought of this essay

3 star(s)

A good report that includes some A - level detail in the introduction and method, but lacks the level of depth required at A-level in the conclusion and evaluation. To improve:
1) Manipulate data to describe clearly what the experiment suggests about the hypothesis
2)Calculate the standard deviation and comment on the spread of the data
3)Identify all sources of error in the evaluation. Discuss how the errors identified could impact on the reliability of the data and the validity of conclusions. Describe how the procedure could be improved to reduce the impact of errors.

Marked by teacher Kerry jackson 19/02/2012

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