• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Investigation into the rate of reaction of the enzyme catalase in yeast when decomposing hydrogen peroxide.

Extracts from this document...


Investigation into the rate of reaction of the enzyme catalase in yeast when decomposing hydrogen peroxide. Aim To investigate the rate of reaction of catalase when reacted with hydrogen peroxide. The enzyme catalase converts hydrogen peroxide, a by-product of cellular reactions, into water and oxygen for use in other reactions in the formula below; 2H2O2 ?2H2O + O2 Background Knowledge Enzymes have a specific area where they work on the substrate. Enzymes have a specifically "folded" protein location called the active site, where the enzyme-substrate reaction takes place. Enzymes speed up chemical reactions by forming enzyme-substrate complexes and, in this case, releasing hydrogen and water, harmless chemicals instead of poisonous hydrogen peroxide inside living cells. This type of reaction is called an anabolic reaction, where chemicals are split up into smaller particles. The rate of reaction depends on a number of factors, including the optimum temperature and pH (which depends on where they would naturally be occuring in the body) and the ratio of enzyme to substrate as the active site on an enzyme can only work on one substrate at a time. Prediction I think that as I increase the substrate concentration(hydrogen peroxide) the amount of oxygen evolved in a certain time period will increase. The rate steadily increases when a higher concentration substrate is added because more of the active sites of the enzyme, catalase in yeast, are being used which results in more reactions according to kinetic theory so the amount of oxygen released in a given time is higher. ...read more.


Water (ml) % H2O2 5 20 20% 10 15 40% 13 13 50% 15 10 60% 20 5 80% 25 0 100% This will create 6 different concentrations for reactions with yeast. Add known amount of yeast powder to clean test tube and add known volume of water as buffer for pH. This gets clamped as shown in diagram. When ready with stopwatch, add one of the concentrations of H2O2 and take regular readings as to the amount of O2 evolved, i.e every 30s for 3 minutes. Repeat with same concentration of H2O2 and record results. Repeat with new concentration. Trial To find out what amount of enzyme and volume of substrate to use, I had to do a trial. This involved changing the variables and testing to see if it reacted too much or too little. 1st Trial I tried using 2 spatulas of yeast powder, with 5 mls of water as a buffer, and 5 mls of neat H2O2 (20 vols). This caused a vigorous reaction which had the "bubbles" of O2 travelling down the delivery tube and interfering with the amount of O2 evolved. As my variable was the concentration of the H2O2, I thought it would be better to reduce the mass of yeast powder that got added and set a level for the independent variables to use for all the experiments. 2nd Trial Next, I tried only 1 spatula of yeast powder and te rest of the above amounts the same to see if this controlled the reaction to an accurate level. ...read more.


The pattern shown on the graph was made by 6 different concentrations of hydrogen peroxide which gave a good enough range to show clearly what I intended. As can be seen on the graph, there is a slight plateau between 40% and 60% vol of H2O2 and also the gradient at the start of the graph is lower than on the final concentration. This could be because the amount of enzymes in the yeast can vary from sample to sample, therefore possibly reducing the number of active sites available for the substrate. It could also be that at that concentration the number of substrate molecules increases and the enzyme can only split one substrate at once so the oxygen evolved slows down. The only way to see if this is an anomaly is to test more of the yeast at that concentration. But there are no distinct anomalies on the results that I have. This helps to prove the prediction more strongly. Suggestions for improvement Make the measurement of H2O2 and the water amounts in the different concentrations more accurate by using a volumetric pipette and smaller measuring cylinders. Then the numbers of concentrations can be increased as they are more accurate and a smoother curve should be shown on the graph with a steadier gradient. Make some concentrations of H2O2 above 20 vol, (100%) to show what happens when there is an excess of substrate to enzyme. This would, once again, make the graph more accurate as the plateau would be clear. Francesca Spencer 13JC 02/05/07 Page 1 of 5 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells 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 AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    Enzymes - investigate how the substrate concentration (H2O2) affects the activity of catalase on ...

    3 star(s)

    Volume of 2.0 mol/dm3 Hydrogen peroxide solution (cm 3) Volume of distilled water (cm3) 0.4 2.0 8.0 0.8 4.0 6.0 1.0 5.0 5.0 1.2 6.0 4.0 1.6 8.0 2.0 2.0 10.0 0.0 Method * Before starting this experiment ensure that the area being used to carry out the experiment is clear, and put goggles on.

  2. The effect of Copper Sulphate concentration on Catalase activity on Hydrogen Peroxide.

    can be carried out in one, and the temperature of the surroundings remains constant throughout the reaction.

  1. To investigate the rate at which hydrogen peroxide is broken down by the enzyme ...

    I then calculated the average of the results and proceeded to repeat the whole process again, with a lower concentration each time, until all the different concentrations of the catalase solution had been tested. My results from these experiments are shown on the next page.

  2. Catalyse Investigation

    All measurements were taken so that the stopwatch was started once the rubber tubing was sealed and the stopwatch stopped once the manometer fluid had reached the base of the highest marked point. To judge accurately, the point at which the fluid reached the marked line, it was examined at

  1. Investigate how concentration of the enzyme catalase in celery tissue alters the rate of ...

    Temperature: It is possible that the temperature of the solutions may change throughout the experiment, depending on the heating of the room, weather conditions, wind from the windows etc. Constant checks, using a thermometer, are needed to make sure that the temperature of the reactants is constant right the way through the duration of the experiment.

  2. Reaction of Catalase and Hydrogen Peroxide

    This I will do by keeping the air conditioner off, so that the room doesn't become cold and lowers the temperature of the solution. As I am studying the effect of temperature on enzyme-controlled reaction it is necessary that I keep the factors mentioned above constant.

  1. How do temperature and concentration affect the rate of decomposition of hydrogen peroxide by ...

    concentrations of hydrogen peroxide and yeast solution I am going to use I am going to do some preliminary work to see which work best and also what is the easiest and most accurate method for me to collect my oxygen gas.

  2. Investigating the effect of the Temperature on the Enzyme Catalase when it reacts with ...

    This shows that using the catalase enzyme with the strength of 100eu/cm3 it will break down the hydrogen peroxide molecules very quickly forming the two products water and oxygen. I think that if I was to do the 100 eu/cm3 I would gain inaccurate results because if I look at

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