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

Aim This investigation aims to find out how anincrease in the concentration of hydrogen peroxide af

Extracts from this document...

Introduction

Aim This investigation aims to find out how an increase in the concentration of hydrogen peroxide affects the rate at which catalase breaks it down. Introduction Hydrogen peroxide is a dangerous compound formed when oxygen runs into carrier molecules that shuttle electrons to and from sites within our cells. We get these carrier molecules from essential minerals such as riboflavin and niacin. Hydrogen peroxide can attack metal ions and sulphur atoms present in protein. To stop the dangerous actions of this compound, our cells make an enzyme called catalase which converts hydrogen peroxide into water and oxygen. Catalase molecules break down hydrogen peroxide molecules at a very fast rate which is essential to keep the level of hydrogen peroxide at a safe level. The catalase molecules in our body use an iron ion to assist this reaction which is gripped at the centre of a disk-shaped heme group. The enzyme is composed of four identical subunits, each with its own active site buried deep inside. Catalase performs its rapid destruction of hydrogen peroxide in two steps. First, a molecule of hydrogen peroxide binds and is broken apart. One oxygen atom is extracted and attached to the iron atom, and the rest is released as harmless water. Then, a second hydrogen peroxide molecule binds. It is also broken apart and the pieces are combined with the iron-bound oxygen atom, releasing water and oxygen gas. This is the equation of the reaction that occurs when catalase breaks down hydrogen peroxide: 2H2O2 catalase 2H2O + O2. Since they must break down reactive molecules, catalases are unusually stable enzymes. ...read more.

Middle

This diagram shows a rough layout of the apparatus. Step 2- Gathering reactants Place the boat on the electronic scale and press 'on tare' or 'on zero' depending on the scale. This will make the reading say 0.00. Then weigh out approximately 2 grams of grated carrot and place it in a boiling tube. Use the splint to push the carrot down to the bottom of the tube. Put the boiling tube in a test tube rack. Repeat this procedure to obtain 5 boiling tubes of carrot. Measure 2cm� of hydrogen peroxide at the concentration intended to take readings using the syringe. Now secure a rubber bung to the end of the delivery tube (if not attached) and place the other end into the beaker and secure it into the gas burette. The end of the delivery tube with the bung should be used to seal the boiling tube when the hydrogen peroxide is added to the carrot. The stop clock should be started immediately. Step 3- Taking readings When one minute has elapsed, remove the bung from the top of the boiling tube and record the volume of gas collected. Then measure 2cm� of hydrogen peroxide of a different concentration and add it to the next boiling tube with carrot and seal it with the bung. Start the stop clock immediately. Only take readings after one minute and when the volume of gas collected goes beyond 45ml, refill the gas burette with water so more gas can be collected. Step 4- Repeats Repeat the whole experiment so that two readings for each concentration are obtained. ...read more.

Conclusion

To prohibit this happening, I started to remove the bung 2 seconds earlier so that the time was kept constant each time. Concerns also arise as to whether or not there was any trapped air or gas in the delivery tubes. To improve my investigation, I could do a number of things. These include: 1. Extending the concentration of hydrogen peroxide used by increasing the concentration by 1.5% each time. This will increase the range of concentrations and could show the optimum concentration required for catalase to work at its maximum rate. 2. Having a control experiment. This could be achieved by using a temperature where catalase will be denatured or using dead carrot to show that the enzyme is actually present and working effectively. 3. Using the concentrations I have now, I could repeat the experiment until clear consistency is shown in the results. This would improve the accuracy and reliability of my results. 4. Collecting the gas in a different way. This could be done by measuring the time it takes for each concentration to release a certain volume of gas. This would also increase reliability. In general, my results are fairly inaccurate because of the slight change in temperature. The results are quite low in reliability because of the reasons previously mentioned. The validity of my conclusions is assisted by the support my results give to my initial hypothesis but because of the unreliability of my results and the limitations of the range and number of observations, no conclusions could be made concerning the optimum concentration of hydrogen peroxide for catalase. As a result of this, my conclusions can be seen as valid but not in their entirety. ...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

    The effects of Hydrogen Peroxide concentration on the activity of Potato Catalase

    4 star(s)

    Inject the Hydrogen Peroxide into the conical flask. This will displace air which must not enter the measuring cylinder. 8) Immediately place the measuring cylinder over the end of the delivery tube. Record the volume of Oxygen collected every 30 seconds for 5 minutes.

  2. Marked by a teacher

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

    3 star(s)

    Record values in results the table. Reliability I think that this method is accurate and reliable, due to the accuracy of the apparatus being used. Which allows for precise measurements of the volume of gas produced to be taken. Measurements will be taken by the use of a burette to 2 decimal places.

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

    3 x 100 cm3 beakers to contain solutions of H2O2, distilled water and celery extract, for transfer to a syringe. It was hard to organise the solutions made, so a Boiling Tube stand is an essential piece of equipment.

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

    Another way to measure the rate of reaction is to weigh the beaker of the mixture throughout the reaction, however this is another inaccurate way of measurement because the change in the weight of the mixture due to the oxygen is so minimal compared to its volume, and at many

  1. Reaction of Catalase and Hydrogen Peroxide

    The complex stresses chemical bonds forming a transition state. This makes the substrate more reactive. Energy is needed to form this state and the enzyme provides it. The enzyme's site of attachment and the parts that stress the substrate's bonds is known as the active site. Properties Of Enzymes 1) All are globular proteins consisting of coiled polypeptide chains.

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

    If however the shape is changed then the substrate will not react, which means that the enzyme molecule has denatured and changed shape, which shows that the lock will not fit into the key. Diagram of the lock and key theory. 4.Describe in detail, how the experiment will be carried.

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

    There had been hypothesis that the active site was a rigid structure, lacking of malleability, but it has been discovered that it can actually alter its shape slightly in order to perfectly fit around the substrate. This secondary hypothesis, took the name of " induced fit theory".

  2. Catalyse Investigation

    Therefore V=1012*5 5E-8+5 V=1E12 reactions per second per molecule of enzyme. I estimate that there are about 50000 molecules of enzyme per square centimetre. If each cylinder has a surface area of 4 square centimetres the total amount of molecules of enzyme is 1.2E6.

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