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

An Experiment to Find the Effect of Altering pH on the Enzyme Activity of Catalase in Yeast.

Extracts from this document...

Introduction

An Experiment to Find the Effect of Altering pH on the Enzyme Activity of Catalase in Yeast. Null Hypothesis I Predict that there will not be a correlation between altering pH and amount of oxygen produced Alternative Hypothesis I predict that there will be a correlation between altering pH and enzyme activity. I expect my alternative hypothesis to be correct. I predict that increasing the acidity of the yeast solution will decrease the enzyme activity of catalase and therefore lower the rate of reaction and amount of oxygen produced. This is because an extreme pH can denature enzymes because in an acidic solution there is a high concentration of H+ ions. The H+ ions interfere with the active site and change the charge of the R-group of the enzyme. Once the Active site has been altered on an individual molecule of catalase, the substrate of hydrogen peroxide cannot bond with the active site and no decomposition occurs. An extreme alkalinity of pH can also effect the rate of decomposition, and ultimately denature the enzyme as the high concentration of OH- ions in an alkaline solution also effects the charge of the R-group (alkyl group - amino acid) ...read more.

Middle

Instead of giving 28mm, I estimate 35mm to be more conclusive. pH5 in the first attempt was high in relation to the received results for every other attempt. Conclusion The alternative hypothesis was proved correct, with increasing pH an increasing amount of oxygen was produced. Explanation of Conclusion If I exclude the anomalous result of pH6, I have found that the enzyme catalase favours and alkali pH for maximum rate of activity. The optimum pH for catalase is pH8. The rate of activity decreases with decreasing pH as explained in the hypothesis; the high concentration of H+ ions in the solution act to denature the enzyme at very low pHs but begin to effect the active site and change its shape. This is because the attraction between substrate and enzyme is often a result of small electric charges at the active site, and these are disrupted by changes in H+ ion concentration. The high concentration also changes the charge on the alkyl group meaning the substrate cannot fit into the active site according to the 'lock and key' theory of enzyme activity: With increasing pH, the more alkali the buffer solution added to the yeast, the higher the concentration of OH- ions which also change the charge on the R-group and change the shape of the active site. ...read more.

Conclusion

Repeating the experiment to smaller and larger time intervals may increase validity of results, e.g. 60seconds and 230 seconds. During this experiment the effect of pH on the enzyme catalase was overall successful, all controllable variables excluding pH were kept constant. Increasing the ratio of yeast to hydrogen peroxide would alter results as altering enzyme and substrate concentration effects the rate of reaction. If repeated again, changing the concentrations also may show more conclusive results as having the enzyme in excess would give an optimum reaction rate and therefore more accurate results. The surrounding of the experiment were open, meaning more oxygen than necessary could diffuse into the atmosphere. Repeating the experiment in closed surrounds would eliminate marginal error to improve results. This was unfortunately not realistically possible. Care was taken to avoid contamination of apparatus, but sterilised, different apparatus for each repetition would insure more accurate readings. Safety was taken into account, and care was taken when handling the substrate and enzyme solution. The experiment was overall successful, although slightly inconclusive, since the optimum pH was established as pH8, even though this was not the highest pH used in the experiment. Overall the results were accurate, in relation to the variability of components used in the experiment. I proved my alternative hypothesis be correct. ...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. The effect of Copper Sulphate concentration on Catalase activity on Hydrogen Peroxide.

    * I then recorded my results into a table in order for me to be able to produce a graph. Diagram of the apparatus: Risk assessment: Apparatus How can it be dangerous How to prevent Hydrogen peroxide It is a harmful and irritant substance, if it gets in contact with the skin, it will react with it bleaching its colour.

  2. An Investigation Into the Effect of Substrate Concentration On the Rate of Enzyme Activity.

    Discussion The results show that there are trends and patterns in my data. There is quite a big range between the fastest median temperature (2.5 seconds at 80oC) and the slowest median temperature (24.5 seconds at 5oC). The results generally show that as the temperature increases the rate of reaction

  1. Investigating the effect of pH on the activity of an enzyme.

    the enzyme has to react with a longer strip of exposed photographic film. The enzyme will react slower with the longer strip. So using a ruler measure accurate the size of each strip. There are also other factors which are not variables of experiment, which can affect the accuracy, these are: > Measurement techniques.

  2. An Investigation into the Effect of Varying pH on Enzyme Activity

    The concentration of the enzyme and substrate would also affect the rate of reaction as higher concentrations would mean the more chance of an enzyme-substrate complex to be formed. The concentrations of enzyme and protease will therefore be kept constant.

  1. An Investigation to determine the effect of Substrate Concentration on the Enzyme Catalase

    SECONDARY SOURCES From a previous experiment 'the effect of pH on the activity of the enzyme Catalase', which is my so-called secondary source of information, I have gathered material about buffer solutions and which ones work most appropriately with enzymes.

  2. Investigating the Effect of pH on Enzymes

    Changes in pH can affect the rate of reaction as the hydrogen ions can affect the hydrogen bonding in the tertiary structure. Small changes will not denature the enzyme but extreme changes will affect the shape. The introduction of H+ (acidity)

  1. Free essay

    Investigating the effect of PH on the activity of the enzyme catalase.

    By preventing excessive H2O2 to build up the enzyme catalase allows important cellular processes which produce H2O2 as a byproduct of water and oxygen to take place safely. It is a very pale blue liquid which appears colorless in a dilute solution, slightly more viscous than water as it is a weak acid.

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

    So in both of these cases catalase prevents the hydrogen peroxide harming the cell. There are four polypeptide chains in each molecule of catalase. The polypeptide chains consist of over 500 amino acids each. Within the catalase molecule, there are four porphyrin heme groups.

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