• 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
  17. 17
    17
  18. 18
    18
  19. 19
    19

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

Extracts from this document...

Introduction

Saira Hamid AS Biology ByB3(b) coursework. Investigating the effect of pH on the activity of an enzyme. Planning. In this investigation the effect of pH on the activity of protease on exposed photographic film is to be tested. In order to do this the colour change of the test solution will have to be measured, this can be done by measuring the absorbency by using the colorimeter. The results obtained will be from 0.00 being the lowest value; there is no fixed highest value, as this depends on the colour change of the test solution. The experiment will be carried out by reacting the enzyme with the substrate. The enzyme is the protease which is mixed with the pH buffer solution; the substrate is the exposed photographic film. No reaction occurs unless the substrate is present, this will be placed in a water bath and removed after a certain amount of time and colour change will be recorded and absorbency will be measured. Variables. There are many variables in this experiment but the 2 main variables that concern this experiment are: * The independent variable, which is the pH buffer solution, this is the variable that is going to be changed from various pH values between 1-14. * The dependant variable is the absorbency as this is going to be measured, the lowest value is 0.00, the blank solution is most likely to give this result, and is used to zero the colorimeter, but the higher the number the more effect pH has on the activity of protease. The other variables have to be kept controlled and constant so that they don't affect the result. These variables are: > Volume of pH buffer solution. > Volume of protease. > Amount of time for reaction to occur. > Temperature of water bath. > Same size exposed photographic film. * Volume of pH buffer solution: if this is not kept constant for all buffer solutions throughout the experiment, then the experiment will not be fair. ...read more.

Middle

* To each of the buffer solution measure out 2.5cm� of protease and place this in each test tube. * Place these test tubes in a water bath at 37�C until they are all at the same temperature. The water bath is already pre-heated to the right temperature in the incubator water bath. * Now place the photographic film in the test tubes using tweezers. The tweezers are used instead of using fingers as this could cause contamination and start reaction before time. At the same time as placing the film in solution start a stop watch and incubate for 20 min. * When test tubes have been incubated for 20 min remove the photographic film as this stops the reaction. * Whilst waiting for this reaction to occur carry out the control. * To prepare the control pour 2.5cm� of a buffer pH of your own choice into a test tube and place 2.5cm� protease and place in a water bath of 70-80�C * Remove this test tube from water bath once the test tube has reached the temperature of water bath. * The purpose of this control is to see if there is and activity without photographic film. * So when all test tubes are out of there water bath lave them to cool for 10 min before measuring the absorbency in the colorimeter. * Check that each cuvette is of same type and shake substance in test tube and pour equal amounts of the test solution in a cuvette. * Before placing the test solution in the colorimeter check that the colorimeter reading is set to absorbency. * Before testing a solution the colorimeter must be zeroed this done by using a small amount of buffer and protease mixed together which has not been place in a water bath. * Test solutions by placing the cuvette in the colorimeter and remove record reading and zero the colorimeter before next cuvette is inserted. ...read more.

Conclusion

* The experiments should have been repeated in the same day as conditions were more likely to be the same. * The amount of reaction should be increased to about the 30 min as it gives it more time for reaction to occur. * Making sure the number of colorimeter was recorded in order to obtain accurate results. Overall even though I encountered various problems I always found a way to improve them, and ensure that the experiment was carried out as accurately as possible. I followed all the steps of accuracy as above and my results were reliable as I had no anomalous results so therefore my experiment must have been precise and accurate up to a certain extent. Also according to my analysis the graph is also a smooth curve. Also my analysis said that the optimum pH is 2 this is correct as I have supported this with scientific knowledge, this must be true because another example of where pH effects the activity of an enzyme is in the stomach during digestion when proteins have to be broken down by pepsin but it is turned into its active form under high acidic conditions as it can only work under these conditions, for the reason that after pH 2 pepsin becomes denatured and inactive. The apparatus did have its limitations but most of these limitations could not be prevented. The majority of the mistakes were made whilst doing the experiment the first time but this cannot be helped as I have not done this experiment before, so the mistakes I made during the first time were corrected when carrying out the repeats. The techniques which were used in this experiment were of high quality especially in the repeats everything was carried out with care although sometimes thing had to be rushed slightly in order to get the experiment finished, but this was not too bad it just meant working at a faster speed but also taking care. In my experiment I did not encounter any breakages or spillages. So this did not hold me back or stop me from working. ...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. Investigating the effect of temperature on the activity of protease enzyme.

    After this time the two solutions were mixed together and placed back in the water bath for a further 4 minutes, allowing a minute for the result to be taken using the colorimeter. These timings are again based around the preliminary experiment when it took around 5 minutes to see a difference in the solutions at room temperature.

  2. Investigating the Effect of pH on Enzymes

    This means only a small amount of enzyme is required to catalyse a huge number of substrate molecules. This means that providing the temperature and pH conditions are suitable, and that there is an excess of substrate, then the rate of reaction is directly proportional to the enzyme concentration.

  1. Enzymes - find the optimum temperature that a protease enzyme works at.

    Enzymes work in three areas: Respiration Photosynthesis Digestion In this particular experiment I will be looking how the temperature will affect enzymes that are digesting proteins. When enzymes are working there fastest it is called their OPTIMUM, for enzymes their optimum depends on two factors which are temperature and pH level of the solution it is in.

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

    Using a water bath would keep the temperature constant but very difficult as keeping the temperature constant would mean keeping the solution in the water bath until the reaction is complete. However, this would mean that the colorimeter could not be used as it does not go into the water bath.

  1. Biology Coursework: What Effect PH has on Enzyme Activity?

    If a small piece of liver is added to hydrogen peroxide a rapid evolution of oxygen is seen. Catalase is an extremely affective catalyst. One molecule of catalase will decompose forty thousand molecules of hydrogen peroxide a second. PREDICTION Before carrying out this experiment I shall make a prediction.

  2. Investigation to show the effect of temperature on the action of protease on photographic ...

    Theory Enzymes are biological catalysts, made from proteins. A catalyst is a chemical substance which increases the rate of a reaction, but remains unchanged throughout. This is very useful and means an enzyme can be used over and over again. Without enzymes, reactions would be extremely slow, and life would almost stop completely.

  1. The Effect of Temperature on Protease.

    at which spontaneous reactions take place. Enzymes cannot make a reaction occur that would not proceed spontaneously without the enzyme. The same principle apply to reversible reaction. Enzymes do not alter the equilibrium point of reversible reaction. Most biological reactions would take place to slow without enzyme for life to exist.

  2. A photographic company wants to recycle the plastic in exposed (and therefore unusable) photographic ...

    pH is too high or too low for the enzyme, it will become denatured, where the structure of the enzyme is changed so that substrates will no longer be able to fit inside the enzyme and therefore will not be digested.

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