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The Effect of Substrate Concentration on Enzyme Action.

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The Effect of Substrate Concentration on Enzyme Action Aim The aim of this investigation is to determine the effect of substrate concentration on enzyme action. The reaction analysed was that between the substrate hydrogen peroxide and the enzyme catalase found in yeast to break down the hydrogen peroxide. Background Catalase behaves as a catalyst for the conversion of hydrogen peroxide into water and oxygen. Catalase is an example of a particularly efficient enzyme. Catalase has one of the highest turnover numbers for all known enzymes (40,000,000 molecules/second). This high rate shows an importance for the enzymes capability for detoxifying hydrogen peroxide and preventing the formation of carbon dioxide bubbles in the blood and this is why this enzyme is formed in the body. Catalase is made in the liver when found in the body. But for the purpose of this experiment yeast shall be used as the form of catalase. (1) Hydrogen peroxide is a by-product of respiration; it also simplifies the whole process of growing fungi and in the treatment of contaminated waters. Since it was first commercialised in the 1800's, H2O2 production has now grown to over a billion pounds per year (as 100%). In addition to pollution control, H2O2 is used to bleach textiles and paper products, and to manufacture or process foods, minerals, petrochemicals, and consumer products (detergents). Its use for pollution control parallels those of the movement itself - municipal wastewater applications in the 1970's; industrial waste/wastewater applications in the 1980's; and more recently, air applications in the 1990's. It is important however that hydrogen peroxide is broken down, as it is a toxic substance. It blisters the skin and has a metallic taste. The liquid solidifies at -0.41� C (31.4� F). Concentrated solutions are unstable, and the pure liquid may explode violently if heated to a temperature above 100� C (302.4� F). It is soluble in water in all proportions, and the usual commercial forms are a 3% and a 30% aqueous solution. ...read more.


8. Repeat this experiment with each concentration three times to insure that there are no inconsistent results. Hydrogen Peroxide Conc. Volume of 10 vol. Volume of distilled water 100% 100ml 0ml 80% 80ml 20ml 60% 60ml 40ml 40% 40ml 60ml 20% 20ml 80ml Fair Test To make this a fair test, it will be made sure that the same volume of hydrogen peroxide concentrations will be measured out for each concentration's experiments and the same volume and concentration of yeast will be used for each. It will also be made sure that the oxygen produced will not be lost, as it will not have any leaks for this to occur. The volume of oxygen produced in the gas syringe was measured for the same amount of time in each individual experiment. The time intervals that the readings will be taken in will be kept the same and the amount of tests carried out for each concentration also. The variables are the different concentrations of hydrogen peroxide used and the same procedure will be carried out for the making of each concentration. Safety A lab coat and goggles will be worn in case of spillages of the corrosive Hydrogen Peroxide. If a spill occurs it will be mopped up immediately. Results Anomalous Points are marked in bold. Table to Show the Volume of Oxygen Produced when a 100% Concentration of Hydrogen Peroxide is broken down Volume of Oxygen (ml) Time (s) 1st 2nd 3rd Average 0 0 0 0 0 10 4 4 4 4 20 10 7 9 9 30 19 10 14 14 40 28 16 21 22 50 35 23 28 29 60 44 29 36 36 70 50 35 41 42 80 55 40 46 47 90 63 47 51 54 100 68 52 58 55 110 69 55 62 62 120 73 57 65 65 Table to Show the Volume of Oxygen Produced when an 80% Concentration of Hydrogen Peroxide is broken down Volume of Oxygen (ml) ...read more.


There were some major errors in the procedure for example when the yeast was injected some yeast remained in the delivery tube, but when some air was pulled up into the syringe and then pushed out again the yeast was moved from the delivery tube and fell into the hydrogen peroxide at the bottom of the conical flask. There may have been leaks from the joints in the apparatus that may have caused some oxygen loss, which may have meant that the experiment was not as accurate as may have possibly been hoped. When the yeast was injected some air was displaced in the gas syringe that meant that each experiment started with a reading of between 4 and 6mls of "oxygen" in the syringe this was taken from the final reading to take this into account. The yeast, which was used, is living and so therefore is a variable as it relies on warm temperatures to live but it can change which makes it a variable which was not taken into account when the yeast was decided upon to be used. The pH of the yeast must also be taken into account as if the conditions are varied the experiment could be unfair, as if the enzymes become too acidic or alkali they could denature. To improve the investigation it may be a good idea to do more repetitions of each concentration and to use a narrow concentration range of hydrogen peroxide, of maybe every 10% instead of 20%, so that you can really see the differences and analyse the effect of catalase on hydrogen peroxide a lot more easily and reliably, also it may be effective to warm the yeast before using it in the experiment so that it is used at its optimum. It would be useful if the gas syringe was more accurate so that there would be less deviation so that if error bars were drawn the distribution of results would be shown better, the oxygen could also be collected above water to reduce loss of oxygen. ...read more.

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Here's what a teacher thought of this essay

4 star(s)

This is a very good investigation in to the effect of substrate concentration on enzyme action.
The scientific theory for the background information was excellent.
This investigation would have been five stars if the structure was improved. In some parts paragraphs were extremely long and would have benefited from being broken down in to smaller sections. The evaluation also contained a lot of repetition from the introduction.

Marked by teacher Jon Borrell 18/07/2013

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