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

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

Extracts from this document...

Introduction

AS-Level Biology Coursework An investigation into the effect of Hydrogen Peroxide concentration on Yeast Catalyse activity Introduction Hydrogen Peroxide (H202) is a by-product of several different metabolic reactions within cells. It is a free radical, and as such can oxidise biological molecules, therefore damaging or killing the cell which produced it. To protect themselves, cells synthesise from amino acids Catalase, an enzyme which catalyses the decomposition of Hydrogen Peroxide into water and oxygen. H202 --> 2H20 + 02 Catalase lowers the activation energy required for this reaction to take place, thus speeding up the rate at which H2O2 is converted to water and oxygen. It does this by having specific active sites; places on the molecule shaped in a way that fits the shape of Hydrogen Peroxide molecules, encouraging them to bind to the enzyme there. This forms an enzyme-substrate complex. Catalase like all enzymes is a globular protein, but as well as its polypeptide chains, Catalase contains a prosthetic group, haem (also found in Haemoglobin). The Iron atom in the haem group facilitates the breaking of the bonds between atoms in the H2O2 molecules, bound to the active sites of the Catalase. The shape of the overall enzyme-substrate complex encourages this, and the release of the substrate atoms as 2 molecules of water and 1 of oxygen. ...read more.

Middle

4. After 20s, I will remove the bung from the test tube, and record the amount of gas in the cylinder. My measurement of the amount of oxygen released over the incubation time will come from the subtraction of the initial amount of gas from the final amount. 5. I will repeat steps 2 through 4, three times for each of the concentrations of H2O2. 6. To achieve concentrations of 16, 8, 4, and 2moldm-3 is simply a matter of adding water to the previous higher concentration in a proportion of 1:1 therefore halving it's concentration. To get 28moldm-3 I will add 14ml of water to 100ml of 32moldm-3, because... H2O2 is toxic and caustic, and therefore must be handled with care - it is also colourless so I will label the beaker to ensure it's not confused with water. Sources of error I decided to use the inverted cylinder method for measuring the oxygen produced because I think it would provide more reliable and accurate results than the gas syringe method. This is because the gas syringes require a certain amount of pressure to build up before the plunger will move which may effect the accuracy of readings at lower concentrations which I expect will produce little oxygen. ...read more.

Conclusion

To account for this possible weakening of the yeast solution, one would have to repeat the whole investigation, but instead of using one batch of premixed yeast solution for all the experiments, an amount of yeast solution would have to be mixed (from inert dry yeast) just before each trial. This would mean each batch of yeast used would have been in solution for the same amount of time, reducing the suspected error arising from the effective yeast Catalase concentration diminishing over time. Another possible reason for the error could be a mistake in mixing the H2O2 solution. The difference in average measurements between those for 16moldm-3 and 28moldm-3 is only 1 ml, with the measurement of 26 ml of O2 being seen at both concentrations. To determine if this is in fact the reason I would merely have to repeat the experiment for the 28moldm-3 concentration. The anomalous result is very significant in terms of the conclusions that can be drawn. Without further experimentation it is impossible to say for definite whether the result for 32moldm-3 is wrong and conclude Vmax was in fact reached at lower concentrations, (around 28moldm-3), or whether the result at 28moldm-3 is wrong and concentrations up to 32moldm-3 of H2O2 can be decomposed per second by Catalase. ...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

Here's what a teacher thought of this essay

4 star(s)

****
The introduction to this report gave a good summary of the scientific theory needed for this investigation.
The report would have benefited from a clear hypothesis so that the conclusion could have been more certain as to whether the hypothesis had been proved / disproved.
The data collection and recording are excellent.
The analysis focused too much on a potential anomalous result instead of looking at the rest of the data and offering more analysis, but was still good.

Marked by teacher Jon Borrell 18/07/2013

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

    How does the pH affect the activity of amylase

    3 star(s)

    We can also see that at pH3 it took an average of 18.83 minutes for there to be a colour change and at pH8 it took just over 17 minutes for there to be a colour change. From this data we can see that the optimum pH would probably be

  2. Effects of Copper Sulphate on the Activity of Catalase

    This should produce results showing how it differs from the normal reaction. Another important point is that I clean the boiling tube thoroughly if I choose to reuse it or use a clean one each time. This is because any remnants could effect the results.

  1. Investigation of the effect of adding different concentrations of NaCl to an enzyme-substrate (amylase-starch) ...

    take place and therefore speed up the overall rate of reaction without changing the temperature at which the reaction occurs. Enzymes are biological catalysts, with the ability to increase the rate of reaction by a factor of at least a million.

  2. An experiment to investigate the effect of chloride ion concentration on the activity of ...

    Each section of the graph can be explained using the principle of allostery. That is the enzyme has two subunits. Each can exist in two states R and T, and the R state has a greater affinity for the substrate than the T state.

  1. An Investigation Into The Digestion Of Milk By Trypsin.

    Reaction No Reaction No Reaction No Reaction 80 No Reaction No Reaction No Reaction No Reaction Analyse From the results shown on the scatter graph I can say that the optimum temperature was 50�C. The results table shows that after the temperature increased from 50�C the time taken for the

  2. To find out how different concentrations of sucrose solution affect the incipient plasmolysis of ...

    The greatest hypertonic solution should exist at 0.7M, in this solution the root vegetable cylinder should become flaccid causing the protoplast to shrink until it's not exerting any pressure on the cell wall because the net movement of water

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

    As a result, the enzyme molecule can be reused. Only a small amount of enzyme is needed because they can be used repeatedly. http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20101/Bio%20101%20Laboratory/Enzymes/Enzymes.htm Prediction & Scientific explanation: In my aim I introduced the concepts of enzymes and described the chemistry behind the catalysis reaction, as Ill as displaying some

  2. Experiment 3 : Identification Of Food Constituents In Milk

    (n.a, n.d) (http://www.seplessons.org/node/362). When lipids are in an aqueous suspension, the dye will colour them red. Milk K1 shows no red spot suggest that milk K1 is fat free while milk K2 which shows some red spot suggest that it contains a little amount of lipid inside it.

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