• 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

To Investigate an Enzyme-Controlled Reaction.

Extracts from this document...

Introduction

PLAN TO INVESTIGATE AN ENZYME-CONTROLLED REACTION. Prior to planning this experiment an introduction into enzymes and substrates was given. 14/11/02- Week 1 - Discussed enzyme structure and how they work. Properties of enzymes - Activation energy needed for A reaction with or without an enzyme present. Theories of induced fit and lock and key hypothesis. Enzyme/substrate complexes. 21/11/02 - Week 2 - Varying enzyme and substrate concentrations within a Reaction. A BBC computer was used to see how a varying enzyme/ Substrate concentration affects a reaction. A graph was presented on the computer to show rate of reaction The other factors which may affect an enzyme- Controlled reaction were discussed, temperature, pH, Competitive/Non competitive inhibitors. Again, the BBC computer was used to show how these factors influenced a reaction. A class demonstration was performed and observations made of an enzyme-controlled reaction using hydrogen peroxide and potato catalase. After an introduction into enzyme-controlled reactions, I have been asked to investigate one of the factors that may affect the rate of an enzyme-controlled reaction. After taking the above into consideration I have decided to observe if varying potato catalase (enzyme), effects the decomposition of hydrogen peroxide into water and oxygen. To perform this experiment I have decided to vary enzyme concentrations by varying the weight of potato pieces. To observe how varying enzyme concentrations affects the decomposition of hydrogen peroxide, the rate of reaction will be measured by the amount of oxygen released in a fixed time. Consider factors that may affect experiment - temp, pH. 28/11/02 - Week 3 - Practical experiment performed. INVESTIGATION OF THE EFFECT OF ENZYME CONCENTRATION ON A SUBSTRATE The aims of this experiment are to establish if varying the concentration of the enzyme, catalase, affects the rate at which hydrogen peroxide is broken down to form oxygen and water. ...read more.

Middle

Where enzymes are absent in a reaction, energy can be given in the form of temperature or pressure that provides molecules with kinetic energy. This overcomes the energy barrier and, enables them to move faster thus more collisions occur. An increase in collisions gives a greater rate of reaction. In the presence of an enzyme the activation energy is lowered and the reaction will occur more readily, even at low temperatures. An increase in temperature above ( 40 to 45 ) can break delicate hydrogen and Ionic bonds which give the enzyme this specific structure. The substrate molecule will no longer be able to bind to the active site as the enzyme is denatured. The experiment was performed at a constant room temperature ( 15 ) and no source of heat was introduced. A possible source of error could have been slight variations in the room temperature, which may have led to some inaccuracies between varying enzyme concentrations. An improvement to this experiment would be to measure the temperature of the reaction with a thermometer. Some reactions transfer energy to the environment (exothermic reaction), which increases the temperature of the reaction. Energy can also be absorbed from the environment (endothermic reaction), in this case temperature decreases. In both these cases, a more accurate measurement would be obtained by using a thermometer. Enzymes are complex globular protein molecules, which have a specific protein tertiary structure. This structure is formed from basic amino acids, which are formed in a particular sequence. This sequence is held together peptide bonds that link each amino acid. The specific structure of the enzyme is given when a polypeptide chain folds back on itself. This folding occurs because there are different areas of negative and positive charge, which attract each other. ...read more.

Conclusion

Within the experiment I varied enzyme concentration, by using different weights of potato pieces. However the exact quantity of catalase present within the potato tissue was unknown. I tried to compensate for this by repeating the experiment twice. An improvement to this would be use 1 molar solution of catalase that could be diluted to form different concentrations, which could measured more accurately. In trial experiments it was found that when I increased potato catalase, they were not all being covered by the 10ml hydrogen peroxide. From this I decided to cut the circular discs into 4 quarters, and found that they all could be covered in the hydrogen peroxide. This also increased the surface area of the potato catalase. I used this to see how changing potato catalase in weight, influenced the breakdown of hydrogen peroxide, as the quantity and speed of oxygen produced is dependant on the rate of reaction. Initially, once the hydrogen peroxide was inserted onto the potato catalase, it was clear that there was a reaction-taking place as bubbles of oxygen gas were transferred via the delivery tube into the measuring cylinder faster within the first minute. Trail experiments proved that after 1 minute it took too long to get a certain amount of oxygen, so I decided to collect oxygen released in 1 minute. The hydrogen peroxide was kept at 10ml throughout each experiment. In trial experiments a greater amount of hydrogen peroxide was used, but this caused a violent reaction as froth travelled into the delivery tube, which prevented oxygen entering the measuring tube, therefore this would have distorted results. In further investigations of enzyme-controlled reactions the experiment could have been repeated more so to obtain more accurate results and the above suggestions and improvements could be taken into consideration. ...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 Life Processes & 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 GCSE Life Processes & Cells essays

  1. Marked by a teacher

    Investigating the breakdown of hydrogen peroxide by the enzyme catalyse in potatoes.

    4 star(s)

    This result can be explained by the idea that both the hydrogen peroxide and catalase are compromised of particles and that these individual particles collide and react if above a certain level of energy. All my results follow this upward trend quite accurately for all concentrations of the enzymes and illustrate that I correctly hypothesises.

  2. To investigate the effect of enzyme concentration on the activity of catalase in potato ...

    I am going to explain the graphs separately. Rate of reaction graph: From the graph you can see that as the surface area/number of potatoes increases so does the rate of reaction. For example the rate of reaction for 1 potato or for the surface area of 1 potato is 0.05 (ml sec-1)

  1. A investigation into the effect of inhibitor concentration on the enzyme catalase.

    have achieved it may be due to my earlier assumption, where an error may have occurred in my method and preparation and caused these odd results. From carrying out this investigation, I can see that inhibitors have some degree of effect on rate of reaction- the addition of an inhibitor prevents the normal enzyme- substrate complex being formed.

  2. The aim of this experiment is to demonstrate that the substrate Hydrogen Peroxide will ...

    Eventually, increasing the concentration of enzyme had no further effect on the rate of the reaction (see point x on Figure 3) due to the limiting factor of the number of substrate molecules. The enzyme concentration was not be altered in this experiment, as the mass of the potato remained equivalent, however, the surface area of potato (and hence catalase)

  1. Influence of pH on the activity of potato Catalase

    The number of potato slices put in was less than the correct amount that was clearly stated, this would have taken more time and affected the results due to the concentration of potato catalase and the total surface area.

  2. The Effect of Catalase Concentration on the Rate of Hydrogen Peroxide Decomposition

    02 9.9cm3 02 30 1.25cm3 02 1.5cm3 02 6.65cm3 02 5.95cm3 02 15.8cm3 02 40 2.15cm3 02 2.5cm3 02 9.4cm3 02 9.65cm3 02 20.6cm3 02 50 2.95cm3 02 3.8cm3 02 12.5cm3 02 12.5cm3 02 26.5cm3 02 60 3.75cm3 02 5.05cm3 02 15cm3 02 16.85cm3 02 29.35cm3 02 70 4.05cm3 02

  1. Investigating the effect of enzyme catalase concentration on hydrogen peroxide.

    Thus, 12 readings were taken so as to cover a wide range of values for the best results. Two readings were taken so as to confirm the validity of the first once since by taking an average one is not necessarily making one's results more accurate.

  2. My hypothesis is that the higher the concentration of hydrogen peroxide the more catalase ...

    and the margin of error is also quite slim. In the graph from 25% concentration to 50% concentration the line is quite steep and the gradient of the graph becomes less steep from the 50% to 75% concentration and onwards.

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