• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10

Influence of pH on the Activity of Potato Catalase.

Extracts from this document...


Influence of pH on the Activity of Potato Catalase Catalase is found in a vide variety of plant and animal tissues, its use is to break down toxic hydrogen peroxide which is formed as a by-product of biochemical reactions, into the harmless substances, water and oxygen. The rate of activity of many enzymes is largely influenced by changes in the pH level. To show the effect of pH on the enzyme Catalase, an experiment will be conducted where potato-discs of a constant size are placed in solutions of known pH and will react with hydrogen peroxide in the solution. The rate at which oxygen is evolved will be measured using a manometer, thus reflecting the activity of the Catalase in the potato. Requirements for Experiment: - Scalpel/Sharp Cutting Device - Cork Borer - Petri Dish - Boiling Tube (with rubber bung) - Stand (with bosses and clamps) - Manometer Tube (with a select diameter 2mm/3mm) - Beaker - Syringe (5cm�) X2 - Clip - Stop Clock - Pencil - Potato Tubers - Tongs - Test Tube Rack - Hydrogen Peroxide - Citric Acid phosphate buffers, made up as shown below from Na2HPO4 (0.2 mol dm-3) and citric acid (0.1 mol dm-3) to provide 100cm3 of buffer in each case: Buffer pH Na2HPO4 cm3 Hydrogen Peroxide cm3 8.3 5 5 6.3 5 5 4.3 5 5 3.5 5 5 2.8 5 5 Before the experiment it is advised that the pHs should be checked with litmus paper or an electrical pH meter. ...read more.


4) As the reaction begins and oxygen is produced the manometer fluid should be pushed down the left hand side of the manometer tube. Using the stop clock, time how long it takes for the fluid to rise through a distance of 5cm in the right hand side of the tube. During this period gently agitate the boiling tube to ensure that the reaction is occurring at an optimal level. 5) Open the clip at the top of the boiling tube so that the manometer fluid returns to its idle position. Time the evolution of oxygen twice more and work out an average result. 6) Remove the bung and wash out the boiling tube thoroughly. 7) Repeat steps 1-6 another five times, with a fresh set of five potato discs each time and using differing buffer solutions of the chosen pH in turn. 8) For each of the final readings, divide the rate of reaction by 100 by the time taken in seconds for a 5cm rise in the right-hand manometer tube. This provides larger numbers for graph plotting. 9) Collate the results in a table 10) Plot a graph of the rate of reaction against pH for the results found. Setup: Results Table Results of the experiment are displayed as follows: pH Buffer cm3 Hydrogen Peroxide cm3 Time/Seconds 2.8 5 5 129.31 5 5 84.38 5 5 98.91 3.5 5 5 110.04 5 5 75.79 5 5 65.09 4.3 5 5 92.45 5 5 75.16 5 ...read more.


It therefore competes with the substrate for the active site, so the reaction is slower. A non-competitive inhibitor molecule is quite different in structure from the substrate molecule and does not fit into the active site. It binds to another part of the enzyme molecule, changing the shape of the whole enzyme, including the active site, so that it can no longer bind substrate molecules. Non-competitive inhibitors therefore simply reduce the amount of active enzyme; similar to decreasing the enzyme concentration. In conclusion, the presence of these inhibitors will have altered the reaction by increasing or decreasing the rate at which the products are produced. There will have been limitations in the results as the range of buffer solution pHs used in the experiment were inadequate to determine an exact optimal pH for the enzyme Catalase to function. To find the optimal pH, further tests could have been conducted by using pHs with closer intervals within the range of 4.5 and 6.5, where the rate of reaction increases sharply, as shown on the graph by an arrow. By analysing the results and the graphs that were produced, there are no obvious anomalies in the results achieved; however there may have been a slight discrepancy in one result which is marked on the graph/s with a circle. This could have been a consequence of any of the factors mentioned above in the evaluation section. Adam Darrah A-Level Biology 09/05/2007 Influence of pH on the Activity of Potato Catalase ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Patterns of Behaviour essays

  1. Factors Affecting Enzyme Activity

    I will repeat this with numerous different concentrations of liver, fruit or vegetable suspension. I will use a control experiment with a concentration of 0% catalase as this should show that the reaction either does not take place or takes place extremely slowly without catalase.


    solution becomes more affective, which is apparent as the increase of bile salt further increases the surface area of lipids, allowing the lipase to act on all the lipids and break the large molecules down into glycerol or fatty acids, as seen by the increase in the pH fall.

  1. Effect Of Substrate Concentration On The Activity Of Catalase

    If the catalase was used up then another potato would have to be crushed and this could produce catalase of a totally differen from studentcentral.co.uk t concentration which would lead to inaccuracies in the experiment making this an unfair test.

  2. The Effect of Catalase in the Breakdown of Hydrogen Peroxide

    However; it could also mean that the substrates are almost engulfed completely so the reaction is slowing down. From this preliminary experiment I could calculate the volume of oxygen produced and with that I could tell if that the percentage of catalase is effective.

  1. The effect of concentration on the activity of catalase.

    This explains why enzymes are specific to their reactions. It is now found that in some enzymes, the active site changes when the substrate attaches to it. This is for a more accurate fit. This is called the induced fit. When the active site and the substrate join, it forms an enzyme-substrate complex.

  2. To examine the effect of Substrate Concentration (Hydrogen Peroxide) on the rate of an ...

    ensuring that the same batch of Hydrogen Peroxide is used, so that different volumes of oxygen are not produced when different batches are used other variables must be controlled. From Previous work we know that temperature affects enzymic activity. Increased heat energy raises the kinetic energy of the reacting molecules leading to more frequent collisions between substrate and enzyme.

  1. Effect Of Substrate Concentration On The Activity Of Catalase

    Test Tubes 6. Beakers 7. Test Tube Rack 8. Stop Watch 9. Pipette 10. Pipette Filler 11. Tap Water METHOD To test out how the concentration of hydrogen peroxide affects the rate of reaction first set up the apparatus below. 1. Add 2cm3 of yeast to one test tube.

  2. Investigate the effect of changing substrate concentration on the rate of the reaction between ...

    Also, additional product will be formed as the initial amount of reactant is greater. The aspect that I have chosen to investigate in this experiment is the concentration of the substrate, i.e., the hydrogen peroxide. I shall keep changing this factor as it will help me explore how the rate of reaction changes with changing concentration of hydrogen peroxide.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work