• 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
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14
  15. 15
    15
  16. 16
    16

An Investigation into the effect of substrate concentration on the activity of the enzyme catalase.

Extracts from this document...

Introduction

An Investigation into the effect of substrate concentration on the activity of the enzyme catalase. Introduction This experiment is designed to examine how the concentration of the substrate (Hydrogen Peroxide) affects the rate of reaction of the enzyme catalase. Catalase is a particular protein. All enzymes are globular proteins. Enzymes are essential for maintenance of life, because without them reactions occurring in living organisms would be so slow that they would hardly be worth occurring at all. It would be possible to increase the speed of reactions by simply increasing the temperature, but for the temperature to have a significant effect on the rate of reaction the temperature would have to be raised to a level that would kill the organisms by disrupting their membranes, as well as being expensive energetically. This is one of the main advantages of enzymes; they enable metabolic reactions to proceed rapidly while maintaining low temperatures. Activation Energy In many reactions, the substrate will not be converted to a product unless it is temporarily given some extra energy. This energy is called activation energy. Enzymes decrease the activation energy of the reaction, which they catalyse. They achieve this by holding the substrate in such a way that their molecules can react more easily. Reactions that involve enzymes take place much faster at lower temperatures than they would without them. The diagram below shows the enzymes lowering the activation energy. Active Site A few of the amino acids on the surface of the molecule fold inwards to make a specific indentation, called the active site, into which a particular substrate can fit. Once the enzyme and the substrate are joined they form an enzyme-substrate complex. The formation of an enzyme-substrate complex makes it possible for substrate molecules to be brought together to form a product. The product is released and the enzyme is free again to take part in another reaction. Enzymes are unchanged during this process, and so they are able to break more substrate molecules into products. ...read more.

Middle

6. The gas syringe has to be held in place by a clamp. The positioning of this is also important for it must be level otherwise gravity will have an effect on the results. 7. The conical flask and gas syringes need to be connected by a delivery tube; using fairy liquid here may be useful as it can be a bit tight. You need to check the set-up is airtight by gently pulling the gas syringe, if it is brought back to it's original place it means it's airtight, if not the apparatus needs to be double checked. 8. Put a needle onto the end of the syringe, and push this into the suba seal, as quickly as possible you need to squirt the liquid into the conical flask. Once this has been done record the level of the gas syringe, and do so every minute until ten minutes is up. 9. Wash and tidy up all the equipment you used. Safety Hydrogen peroxide will be used throughout this experiment, so goggles must be worn constantly to avoid any damage because hydrogen peroxide is a corrosive chemical. In addition to this gloves must also be worn to protect skin, as minor spillages are common. It is essential to wear a laboratory coat to prevent any chemicals damaging clothing and reaching the skin underneath. In both of the methods a scalpel is used to cut the celery, and if these aren't used sensibly they could cut the skin. Most dangerous however is the needle in method two as the syringe contains hydrogen peroxide. Because of this fact the needle should only be put on the syringe just before it's needed and taken off immediately afterwards. Method Two Preliminary Results Amount of oxygen evolved (cm) Minutes Hydrogen Peroxide 80% ( cm ) Hydrogen Peroxide 20% ( cm ) 0 9 10 1 12 11 2 14 11 3 15 11 4 16 11 5 16 11 6 16 11 7 16 11 8 16 11 ...read more.

Conclusion

As I was using an inverted burette I think I can be quite confident of the accuracy of my measurements, for burettes are very precise and have clearly marked values along the side. Apart from reasons already discussed, the most significant limitation of the method I used is the lack of an airtight environment. Using a gas syringe connected to a suba seal is the obvious solution to this problem, but as I experienced problems with this during my preliminary experiments I thought it wasn't practical to use, but many others from my class were able to produce reliable results from it, so given the chance where I could be assured the results were reliable I would use a gas syringe. Improvement on accuracy of results could be achieved by minor changes such as increasing the number of repeats used, so that the average was worked out using more sets of results and overall improving it's reliability. As oxygen was still being produced at a steady rate when I terminated the experiment after 10 minutes, it could prove useful to continue recording the results for a further 10 minute as this might mean more trends could be identified between the different concentrations levels and the analysis could be covered in more depth. I have focused mainly upon the discrepancy between the 80% and 100% concentration levels but there are also other points for discussion. If you look at the table displaying the results recorded for the 60% solution of hydrogen peroxide solution you'll see that the first repeat produced reasonably more oxygen than the second two repeats, I think this can be explained using reasons I outlined earlier, the first repeat was carried out on a different day to the other two so the hydrogen peroxide and celery would have been different and this lead to a discrepancy. I believe that the first result is probably most accurate. This also explains why the lines on the graph for the 60% and 40% are so close as the 60% should probably have been higher. ...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

    Investigating the breakdown of hydrogen peroxide using celery tissue to supply the enzyme catalyst

    4 star(s)

    on the scale of the burette and was able to be read off. Problems to overcome The setting up of the experiment will be very tricky, as the stop clock has to be started and then as quickly as possible, the H202 added, and the delivery tube put up the

  2. Marked by a teacher

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

    4 star(s)

    the active sites of the enzymes became more and more occupied until the substrate had to wait for an enzyme to become available before it could bind. Section 4 - Evaluation Overall, I am pleased with my results for this experiment.

  1. Marked by a teacher

    Factors effecting enzyme activity

    4 star(s)

    the most oxygen, the one which gave off the most oxygen would be the one which I use in my real experiments because this would then give me the best results. By doing my preliminary experiments, I worked out how often I should take my readings because I looked at

  2. Marked by a teacher

    An investigation into the effect of Hydrogen Peroxide concentration on Yeast Catalyse activity

    4 star(s)

    For Catalase this is around neutral, i.e. pH 7. Therefore I will add 5cm3 of pH 7 buffer to 200cm3 of yeast solution, (a proportion suggested as suitable by a scientist), and stir the mixture to ensure an even pH throughout. 4: Quantity of Hydrogen Peroxide and Yeast solution.

  1. Marked by a teacher

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

    3 star(s)

    a reliable and accurate set of results that display the effect changing the dependant variable has to this experiment. Below is a table of how these variables will affect the experiment and how it will be controlled. Variable Why is it a variable How it will be controlled Substrate concentration (Independent)

  2. Reaction of Catalase and Hydrogen Peroxide

    Thus the rate of the reaction will increase. The heat of the molecule inside the system will increase. As the temperature of the system is increased the internal energy of the molecules in the system will increase. The internal energy of the molecules may include the translocation energy, vibration energy

  1. Catalyse Investigation

    Amylase The Effect Or Varying Enzyme Concentration On The Breakdown Of Hydrogen Peroxide In The Presence of [Save this essay for later viewing] [View Saved Essays] Hypothesis - Hydrogen peroxide will breakdown to oxygen and water in the presence of Catalase.

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

    The filter paper sinks to the bottom of the hydrogen peroxide solution forming oxygen, it's the gas oxygen that makes the filter paper float back to the top. Now if the filter paper always has the same area, then it will take the same amount of oxygen gas to make it rise back up to the top.

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