• 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
  11. 11
  12. 12

Rate of reaction

Extracts from this document...


EXPERIMENT TO INVESTIGATE THE EFFECTS OF DIFFERENT PH MEASUREMENT ON THE ACTIVITY OF THE ENZYME CATALASE Aim: To investigate the effects of different PH measurements on the activities of the enzyme catalase. Hypothesis: As the measure of the pH is increased, the enzyme's activity will also increase. The enzymes optimum pH will be around 7-8 and after this Ph is reached, increase in the pH will decrease enzyme activity. Theory: Enzymes are protein molecules that can be defined as biological catalysts. A catalyst is a substance that initiates or accelerates a chemical reaction without itself being affected by the reaction. Enzymes lower the activation energy of a reaction, so that the rate of the reaction increases. The concentration of the hydrogen ions affects the ionic bonds. If the pH changes much from the enzyme's optimum, the chemical nature of the amino acids can change and this may result a change in the bonds and so the tertiary structure may break down. The active site of the enzyme will be disrupted and so the enzyme will be denatured. Enzyme and substrate concentration can also affect the rate of reaction. At low enzyme concentrations, there is great competition for the active sites and the rate of reaction is low. As the enzyme concentration increases, there are more active sites available and so more substrates can bind unto the active sites enabling the rate of reaction to proceed at a faster rate. Eventually, increasing the enzyme concentration beyond a certain pint has no effect because the substrate concentration becomes a limiting factor. This point is the optimal concentration. At a low substrate concentration there are many unoccupied active sites and this means that the rate of reaction is low. When more substrate molecules are added, more enzyme-substrate complexes can be formed as there are more active sites and the rate of reaction increases. Again, increasing the substrate concentration further passed the optimal point will only result a decrease reaction rate. ...read more.


o Time using a clock how far the liquid in the manometer travels in a space of 3 minutes. Measurements should be taken every one minute until the 3 minute time is reached. Variable Control Dependent - the rate of the reaction Independent - the concentration of the catalase * The pH is going to change as the aim of the experiment is to investigate how different pH affects the enzyme activity. * The enzyme quantity will be kept as close as possible to been constant. This is because if the enzyme quantity changes, the pH will not be the only variable affecting enzyme activity as enzyme concentration can also affect the rate of reaction * The temperature should be kept constant because it can also affect enzyme activity. * The same volume of pH concentrations to be used. This will ensure fair results. A syringe will be used to take the accurate measurements. Risk Assessment 1) Laboratory cloths should be properly worn during the cause of the experiment. 2) Goggles and gloves should be worn at all times to prevent solutions like the hydrogen peroxide from reaching the skin. Hydrogen peroxide is a toxic and so great care should be taken whilst it is been used. 3) To handle all apparatus (mainly scalpel) with care. This is because such equipments can easily inflict harm on an individual if not handled with the appropriate care due to its sharp edges. TABLE OF RESULTS First Trial Number of potato discs pH concentration Distance travelled/Time (min) 1 minute 2 minutes 3 minutes 10 4 2.5cm 4.2cm 5.5cm 10 5 4.1cm 6.0cm 7.0cm 10 6 4.0cm 6.3cm 8.7cm 10 7 6.7cm 9.5cm 10.4cm 10 8 6.4cm 9.1cm 10.2cm 10 9 6.3cm 9.2cm 10.0cm Second Trial Number of potato discs pH concentration Distance travelled/Time (min) 1 minute 2 minutes 3 minutes 10 4 3.0cm 4.3cm 5.3cm 10 5 4.0cm 5.9cm 7.5cm 10 6 4.3cm 6.4cm 8.6cm 10 7 6.5cm 9.4cm 11.2cm 10 8 5.8cm 8.9cm 10.5cm 10 9 6.2cm 8.7cm 11.0cm Average and Rate of reaction table pH Concentration Average distance travelled in 3mins. ...read more.


Evaluation - Improvements If I was to do the experiment again, I would take some further factors into consideration; a) I would use a wider range of concentration of enzyme to acquire a greater range of results to investigate and compare. b) I would use smaller test tubes because this could have an effect on the amount of collisions that occur and so the rate of reactions could possibly increase. The closer the particles are, the more chance of enzyme-substrate complexes been formed. c) I could use a gas syringe with a glass pipe as an alternative instead of the manometer, as some gas may have been lost through it. d) Possibly use more potatoes in grams because it could increase the amount of gas produced e) I would also use a more accurate concentration of catalase; example by using a solution. Evaluation - Protocol change The procedure could be improved although the results do give adequate conclusions. Improvements in the protocol would help remove certain errors and improve accuracy of the results. Using a method that doesn't require the manometer could result accurate readings been taken. This is because the manometer had some setbacks which included the liquid overflowing once the reaction was fast and over a long period of time. Also the liquid in the manometer sometimes had to restart its travel due to a limited space for it to travel. This occurred mainly in the reaction with the pH 7. A suggestion of such strategy would be to use equipments which didn't require the use of the manometer. Example of such strategy had been presented below: i) ii) Overall, I believe the experiment was a success and so I can conclude that the aim was achieved with the prediction been correct; if the amount of enzyme is kept constant and the pH is then gradually instead, the reaction rate will increase until the optimum working rate is achieved. ?? ?? ?? ?? Charles Badu-Boateng E1 Candidate Number: 0349 1 Biology Coursework ...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)

    two sets of results and give me a more reliable set of results. To keep the dilutions of hydrogen peroxide remains at the required concentrations until use.

  2. Free essay

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

    [1] The active site of an enzyme is the binding site between enzyme and substrate. The structure of the active site allows for the recognition of the substrate. If an enzyme is subjected to high temperatures or a pH far from its optimum it will become denatured and cease to function.

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

    As the copper sulphate concentration goes down, more oxygen is produced, a higher concentration of distilled water means a loIr concentration of copper sulphate: there are less copper ions present in the solution, there will be less copper ions displacing less Haem groups and breaking less disulphide bonds, resulting in a loIr percentage of catalase molecules being denatured.

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

    This means that different parts of the solution could be more reactive than another, which could have caused slight inaccuracies. To try and prevent this I shook up the enzyme solution for each experiment before adding the substrate. Any slight differences in these results could also be due to human reaction time.

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

    things, animals and in plants shows that water is unlikely to damage the catalase molecules. Water is also highly un-reactive - it will not act as an oxidising agent (it won't bond with or take any electrons from the catalase molecule).

  2. Factors That Affect the Rate of an Enzyme Reaction.

    result might be gained, and I wouldn't even know because I wouldn't have any data to compare it with. If I get any anomalous results, which are results that look inaccurate, don't fit in with the pattern of the other results and in this experiment are results not within 20 seconds of each other.

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

    clothing, rinse for at least 15 minutes and seek medical attention if problems occur. > Eye exposure: Vapours are corrosive and can be damaging to eyes. Symptoms include pain, redness and blurred vision. Splashes may cause tissue destruction. Wash eyes for 15 minutes, lifting upper and lower eyelids.

  2. This is an experiment to show how different concentration of celery tissue enzyme, catalase ...

    there are few free enzyme molecules, so adding more substrate doesn't make much difference Inhibitors: - Inhibitors are substances, which alter the enzymes activation. There are two main types of inhibitors: * Competitive inhibitor * Non-competitive inhibitors Competitive inhibitors: - Competitive inhibitors have the same shape as substrate and therefore

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