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Does ethanol causes greater inhibition of pig liver catalase than of yeast catalase

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Does ethanol causes greater inhibition of pig liver catalase than of yeast catalase? Introduction In my experiment I am using catalase. Catalase is an enzyme that breaks down hydrogen peroxide (H2O2). Hydrogen Peroxide is a waste product left after aerobic respiration. Hydrogen Peroxide is harmful to cells if not broken down. This means that catalase is present in nearly every cell. Catalase breaks Hydrogen Peroxide down into oxygen and water, as it is an enzyme it is not used up in the reaction Catalase Hydrogen Peroxide ???? Water + Oxygen Catalase 2H2O2 ???? 2H2O + O2 Catalase is an extremely efficient enzyme with one of the highest turnover number of any enzyme (the number of molecules of substrate broken down by a single molecule of enzyme per second.). Catalase like all other enzymes is a globular protein. Enzymes have a very precise (three-dimensional) tertiary structure. This structure is held in shape by hydrogen bonds and disulphide bonds. These bonds make up the shape of the active site. The active site of an enzyme is where an enzyme binds onto the substrate. The active site shape is complimentary to the substrate molecule shape. The substrate molecule fits into the active site and is held there until the reaction is finished. The substrate is then released and the enzyme is ready to take part in another reaction This is known as the lock and key hypothesis. Just as only the right key will fit a lock, so only the right substrate has the right shape to fit into the active site. But scientists have come up with the Induced Fit Hypothesis. When the substrate comes into contact with the enzyme the active site will change shape to allow the substrate to bind with it and react this would stop things like water molecules binding with the active site as the active site would not bind until it came into contact with the substrate. ...read more.


I will then make the beads by mixing 20cm3 of liver solution with 10cm3 of sodium alginate. I will then make small balls of this by syringing it in drops to a beaker of calcium chloride which will make it set hard. I will then wash the beads off in water to get the calcium chloride off. I will use the same process for the yeast beads I will mix 20cm3 yeast solution with 10 cm3 sodium alginate and dropping it through a syringe into a beaker of calcium chloride. If any beads floated in the calcium chloride I discarded them as it already meant they had air inside 2. Make Hydrogen Peroxide and Ethanol solutions I will make up one concentration of 0.05 mol.dm-3 hydrogen peroxide by mixing together 5cm3 of hydrogen peroxide with 95cm3 of distilled water. I will use this to make up my hydrogen peroxide/ethanol solution. I will mix these up with the amounts shown in the table below Table 2: The production of a range of ethanol concentrations Ethanol Concentration made (mol.dm-3) Volume of 0.05mol.dm-3 H2O2 solution (cm3) Volume of 1 mol.dm-3 ethanol (cm3) Volume of water (cm3) 0.00 15 0.00 5.0 0.01 15 0.5 4.5 0.02 15 1.0 4.0 0.03 15 1.5 3.5 0.04 15 2.0 3.0 0.05 15 2.5 2.5 0.06 15 0.3 2.0 I will make 2 test tubes of each solution 1 for the liver catalase and one for the yeast catalase. I will make the solution at the same time so that they were exactly the same concentrations. I will label each test tube so I know what it is. 3. Dropping the beads in I was now ready to start the experiment. I started at the 0.00 concentration of ethanol. I would take one bead about the 5mm size and would drop that into the hydrogen peroxide/ethanol solution. I started timing as soon as the bead broke the surface so I timed its decent to the bottom and then back up. ...read more.


I would try timing it to 0.1 of a second instead of just to 1 second This would make my results more accurate and give me a better picture of the inhibiting. I would also like to measure the concentrations out to 0.005 mol.dm-3 This would make the more accurate timing useful and would allow me to see a better and more accurate graph. I would also like to try and come up with a way of measuring the size of the beads better I could maybe do it by mass instead of size but then the ones with a bigger surface area would rise quicker instead of the lighter ones, so I'm not sure how I would do that. The main change I would make to my experiment is using a gas syringe this would sort out my problem of having bubbles not carry the bead up. I would have a certain time limit and count how much gas it makes in that time. You are then though have a problem of when it rises to the surface not all of it is touching the solution so it would reduce its own surface area. So you have to find a way of keeping it under. I would also like to use fresh hydrogen peroxide solutions for every try. As this would solve the problem of the solution diluting itself as I do more repeats. Another thing I would change is do more repeats of each concentration I would probably do 6 repeats for each one which would take longer but would be worth it. It should make it easier to work out which results are anomalies. Conclusion My results don't give enough evidence to accept the hypothesis. In fact, they show that there is not really any much difference in the degree of total inhibition at the strongest concentration of ethanol. I would need to use a statistical test such as the Mann Whitney u test to work out if the difference between the inhibition of the two yeasts is significant. ?? ?? ?? ?? ...read more.

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