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Rate of enzymes reaction and the concentration of substrate

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Introduction

Rate of enzymes reaction and the concentration of substrate Aim to investigate the effect of substrate concentration on rate of enzyme reaction, using immobilised catalase. Hypothesis the rate of reaction will be increasing until the limited amount of enzymes. After the point of limit, the reaction rate will be stop increasing and stay at the certain point. Apparatus Syringes Various sized beakers Stop clock Manometer Distilled water Tweezers 6 boiling tubes Pieces of liver Homogeniser Buffer solution (PH7) Test tube rack Sodium alginate solution (2%) Blender Calcium chloride solution (1.5%) Hydrogen peroxide (20 volume) Ruler Glass rods Marker Risk assessment : 1. A hot water bath was used, special attention should be paid. 2. hydrogen peroxide solution was used, it should be handled with care as it is irritant. 3. Safety glasses should be worn for eye protection. 4. Enzymes are biologically active proteins, it should be handled with care. We should avoid direct contact or inhalation. 5. If we spill any peroxide solution or enzyme, spillages should be cleaned up immediately. We should not allow them to dry and generate dust. Precaution 1. Instruction should be read carefully before starting the experiment. We should know clearly that we have to vary the concentration of substrate and investigate the reaction of different concentration of amylase with a fixed amount and concentration of enzyme. 2. All test tubes should be labelled according to their contents. 3. We should work on a concentration at a time to avoid confusion. 4. ...read more.

Middle

4. Use syringes to measure 20 cm of undiluted peroxide and pill a conical flask. 5. Seal the conical flask with this devised cork immediately which the end of the rubber tube connected to the gas syringe to measure the gas generated. 6. Let the reaction continue for 10 min and record the result. 7. Repeat the identical experiments to the other solutions. Result The result I obtained is shown below. Conc. of solution (M) Oxygen produced(cm ) 1st Oxygen produced(cm ) 2nd Average amount of oxygen produced(cm ) 0 0 0 0 0.178 12 10 11 0.44 36 31 33.5 0.89 84 78 81 1.34 111 107 109 1.78 155 163 159 As the graph attached, we can see the graph is almost a straight line and the concentration of substrate is directly proportional to the rate of reaction. Analysis Enzymes are highly specific. Each enzyme will only catalyse one reaction. The substance with which the enzyme( in this experiment the enzyme was catalase in peroxisomes) combines is known as the substrate (hydrogen peroxide is the substrate in this experiment), which combines with the enzyme at a particular place on the enzyme's surface called the active site. Since hydrogen peroxide is the by-product of the metabolism reaction, which is a potentially very harmful oxidising agent, our body have to decompose it into harmless water and oxygen by using catalase. ...read more.

Conclusion

* Using syringe to make the solution was not precise. At the beginning of the experiment, we made up a 20 cm of a particular concentration of peroxide solutions . However, we have to use the syringe which we have to think and calculate to made up the acquired volume such as 18 cm (use 10cm syringe and the 5 cm of syringe, finally 3 cm of syringe.) The volume in one test tube might not be exactly the same as the amount that required. Therefore, this also make the data less accurate. Using pipette is more accurate. * The number of immobilised enzymes in each beads and the size of beads can be different from each other. Conclusion From this experiment, we could conclude that as the concentration of substrate increases, provided that there is an excess of enzyme molecules, the rate of reaction increases in proportional to the concentration of enzymes. Further work We could also investigate how the enzyme concentration affects the rate of reaction. We could vary the enzyme concentration, but keep the concentration of substrate molecules constant. Since the rate of the reaction depends on the rate of formation of enzyme-substrate complexes, the rate of reaction will increases as the enzyme concentration increases, but only until all substrate molecules are being used. This shows that both enzyme and substrate concentration affect the rate of reaction. And as there was no point where all enzyme molecules are occupied (saturated), we can increase the concentration of hydrogen peroxide to investigate the maximum point of catalase for hydrogen peroxide. ...read more.

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