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

Investigation into the effect of substrate concentration on the rate of hydrogen peroxide decomposition by the enzyme catalase.

Extracts from this document...

Introduction

Investigation into the effect of substrate concentration on the rate of hydrogen peroxide decomposition by the enzyme catalase. Aim An experiment is to be conducted to determine how varying the concentration of the substrate H2O2 used will affect the rate of its catabolic decomposition into oxygen and water due to a fixed amount of the enzyme catalase. The enzyme catalase used is in the form of potato cylinders (since catalase is found in potatoes and that potatoes can be easily cut into cylindrical shapes to give maximum surface area). A chemical equation of the reaction is shown: 2H2O2 (aq) --> 2H2O (l) + O2 (g) It can be seen that the number of oxygen molecules produced will be proportional to the number of H2O2 molecules decomposed. Therefore the amount of O2 produced in a certain time as the product of the reaction can be used to determine the rate of this catabolic reaction. Introduction The above reaction only occurs at a noticeable rate when there is catalase present. Catalase decomposition of hydrogen peroxide has a turn over rate of 5,000,000 molecules (5,000,000 H2O2 molecules are decomposed by one catalase enzyme in one minute). It would require 300 years for the same number of H2O2 molecules to be decomposed without the presence of catalase. (Villee C., Dethier V., 1970, Biological Principles and Processes, W.B. Saunders Co) The enzyme catalase is seen to dramatically increase the decomposition rate of H2O2. This is due to the fact that enzymes (a globular protein) reduce the activation energy of the reaction. This is to say, less energy is required to start the reaction so that more reactions can occur. The energy transfer diagram below illustrates this point: Hypothesis Presently, there are two theories as to how enzyme molecules interact with their substrate molecules to reduce the activation energy: Lock & Key hypothesis: This is the theory that every enzyme has an enzyme active sites of a specific shape corresponding to the substrate that it will attach to, as a key fits a lock. ...read more.

Middle

As oxygen is collected in it, the water is displaced and the receding water level will tell us the volume of oxygen produced. Up turned burette: This will be used in the exact same way as an up turned measuring cylinder. This advantage this will have over the measuring cylinder is that it will measure to �0.1cm3, giving an accuracy ten times that of the measuring cylinder. Bubble counting with up turned boiling tube: An up turned water filled boiling tube could be used for oxygen to be collected in it. Since oxygen is given off in the form of bubbles, the number of bubbles given off could be used to calculate the reaction rate. A boiling tube is preferred to a normal test tube due to its larger volume. Gas syringe: This is a syringe especially adapted so that it self fills as gases (often under low pressures) enters it. It will be able to record the amount of oxygen given off by our reaction to a suitable degree of accuracy. I have decided to use the gas syringe to determine the amount of oxygen produced. This decision was made because: 1. The test tube method will not give us definite quantitative results. Unlike the other methods, the volume of the oxygen produced is unknown. It will also be hard to count the number of bubbles given off if the reaction rate is particularly high. 2. All of the methods of using the displacing of water to measure the amount oxygen produced are sound in theory. In practical, however, they will be far more time consuming to be set up. For example, to reset the syringe to a reading of 0 all that has to be done is for me to push back its plunger. On the other hand, the burette/measuring cylinder will have to be refilled with water and carefully turned upside down under water, this is a far more time consuming technique. ...read more.

Conclusion

This makes sure as little oxygen escape as possible. The stop watch is only started when the rubber bun is placed so that the volume of O2 recorded is still oxygen produced in 60sec. In addition to the above, each test for each concentration of H2O2 will be repeated 3 times so an average will be able to be obtained to further enhance the reliability of the results. Use of results The results for each test will be collected in the following table` Conc. Of H2O2 (%) O2 Produced (cm3) Average O2 produced (cm3)* Reaction rate (cm3 min-1) 1 2 3 20 40 60 80 100 *Any clearly anomalous results will be ignored in the taking of an average. The rate of reaction is measured quantitatively in the form of cm3 of O2 produced per minute. This value can be plotted against the concentration of H2O2 as the variable on the x axis on a graph. The pattern shown by the graph can be characterized with a trend line. From the graph, a relationship between the concentration of the substrate and its reaction rate can be established as well as quantitative analysis for the Michaelis constant (the substrate concentration where the reaction rate is half of Vmax). (M B V Roberts, 1971, Biology a functional approach, Thomas Nelson and Sons Ltd) Risk Assessment Care will have to be taken with laboratory glassware. If any glassware is broken, quickly sweep up and put into broken glass bin. Care should be taken with sharp objects such as the scalpel. Chemical: Chemical Hazards Risks Likelihood Control Measures Hydrogen peroxide solution 20vol. Irritant Irritation to the skin and respiratory system Medium/low Wear Protective clothing and gloves and avoid inhaling. Irritation to the eyes. Low Wear protective goggles May cause nausea, vomiting and internal bleeding if ingested Very low If ingested, wash out mouth thoroughly with water and give plenty of water to drink. OBTAIN MEDICAL ATTENTION. Hazards data obtained from Health and Safety information, BDH. ...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. The Decomposition of H2O2 using Catalase, in yeast as a catalyst.

    there are more yeast particles in given volume, meaning that more collisions take place. Using an accurate balance to ensure the mass of yeast used stays the same Apparatus For this experiment I will need: * Retort Stand * Gas Syringe * Delivery tube with bung * Boiling tube *

  2. THE EFFECT OF BILE SALT ON THE ACTION OF THE ENZYME LIPASE

    Chemicals required * Distilled water. * Sodium hydroxide. * Lipase (enzyme). * Full-fat cream, lipid (substrate). * Bile salt. Concentration of bile salt Table two below, demonstrates how to maintain the different concentrations of bile salt, which is essential once conducting the experiment, in order to observe the affect of bile salt on the activity of lipase on lipids.

  1. Factors Affecting the Rate of Catalytic Decomposition of Hydrogen Peroxide.

    This is a suitable amount of points to determine whether there is a trend and enough to draw a good line of best fit. I have decided that to obtain the best possible accuracy, a repeat result will be taken, and if the two agree, then they will be averaged to give the point to be plotted.

  2. Effect Of Substrate Concentration On The Activity Of Catalase

    This can be explained as a lock and key model, where the lock and key are specific to each other, only, that there are many of the same kinds of lock and key when it come to the enzymes. Just as lock and keys have three-dimensional shapes, proteins are also three-dimensional.

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

    34.2 14.7 6 30.8 18.5 25.5 23.4 8 29.3 20 17.8 31.1 10 28.5 20.8 12.5 36.4 Average Amount: 35.9 13.5 24.8 19 Peeled Potato Percentage of Catalase: 50% Percentage of Catalase: 100% Time: Initial Reading (cm3): Volume of Oxygen (cm3): Initial Reading (cm3): Volume of Oxygen (cm3): 0 49.8

  2. The effect of aspirin on the action of bovine liver catalase

    by the time taken. Table 4. The rate of reactions for different aspirin concentrations. Aspirin concentration (gdm� �) Rate of reaction (in terms of oxygen produced) (mm3 s-1) 0 2.62 2.42 2.51 2.42 2.51 2.62 5 2.09 2.17 2.09 2.24 2.24 2.09 10 1.90 1.96 1.80 1.96 1.80 1.85 15 1.70 1.70 1.75 1.65

  1. Enzymes - show how substrate concentration affects the rate of reaction for an enzyme ...

    error = Smallest division � 100 Measured quantity Smallest division of the burette = +/-0.05cm�, this is the scale to which I will be able to read as accurate to. Measured quantity is the volume of oxygen = 0.85 cm� on average collected.

  2. Investigation On The Enzyme Trypsin

    12 111 113 113 114 115 113.2 0.0088 13 112 115 114 114 116 114.2 0.0087 14 115 117 117 117 119 117 0.0085 15 120 121 119 123 124 121.4 0.0082 16 123 124 126 126 127 126.5 0.0079 17 131 131 129 132 128 130.2 0.0077 18 135

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