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Effect of Temperature and pH on Enzyme Action Lab report sample

Effect of Temperature and pH on Enzyme Action


The bodies of living things are composed of cells. The cells do undergo the body metabolic activities which are very fundamental fro the maintenance of the life of the living thing. The metabolic reactions in the body need to be sped up by the actions of the enzymes present in the body cells. However, in many cases, the functions of the enzymes have been faced with various environmental conditions which then affect their final efficiency and outcome. This experiment is therefore conducted to make out the effects of the variations in the level of temperature and ph on the actions of the enzymes activity.

The experiments were done by varying the conditions of pH and temperatures and subjecting the enzymes to the changes in the conditions. The experiment showed that the enzyme actions are most active at the pH close to seven which is relatively the closer ph of the body. Extremes of pH lower the levels of enzyme activity. Temperature experiment however did not show the expected results possibly die to the errors made in making of the experiment samples and arrangements or reading of the experiment scores.


Enzymes are organic materials found within the living cells of the body to majorly act as the catalysts to the body chemical reactions. The major work of the enzymes in the body is to catalyze the rates of reactions which take place in the body, though they do not take part in such chemical reactions, that is, they are not used chemically in the reactions hence they are special kinds of organic materials. The living cells in the body are ever undergoing chemical changes so as to remain a live, and the work of these enzymes is to ensure that there is low activation energy for the body reactions so as to make the reactions run faster (Farabee).

The enzymes in the body have special shapes and always work on and changes specific substances called the substrates. During the time of the chemical change of the substrates, enzymes must come into contact with them at the places called the active sites. It is important to not that the substrate and the enzyme must have a conformity in their structures and shapes so that they fits well into one another for efficient changes. Once the change of the substrate is complete, the enzyme is detached from the substrate and regains its original shape ready for a new substrate. This means that in most cases, enzymes are reusable and are very adaptable to the substrates.

This experiment is therefore carried out to make out the factors which may influence the activities of the enzymes in their work of catalyzing the rates of reactions in the body. The major focus is placed on the effects of changes on the ph and temperature in the environment of the enzymes affects their activity.

Materials and Methods


  • Equipment:
    • Colorimeter
  • Other Materials:
    • Bottle of distilled water
    • Bottle of turnip extract
    • Bottle of substrate mix
    • Cuvettes for colorimeter
    • Pipetter (green for 5-10 ml pipettes)
    • Pipetters (5 ml)
    • Micropipette (100-1000 µl) and tips
    • Box of kim-wipes


This experiment was designed and conducted to find out how the changes in the pH and the temperature in the environment of the enzyme would affect the enzyme activity. It is carried out for a total of sixty seconds with the measurements taken and recorded after every three seconds. After which, a series of similar experiment was conducted as the pH adjusted to the levels of2, 7, and 10 and temperature was adjusted to 4°C, 22°C, and 37°C.


Experimental Setup for Temperature Experiment
Temperature Distilled Water Turnip Extract Substrate Mix Total
Ice Water 4°C 2.2 ml 400 µl 400 µl 3.0 ml
Room Temp. 22°C 2.2 ml 400 µl 400 µl 3.0 ml
Body Temp. 37°C 2.2 ml 400 µl 400 µl 3.0 ml


Absorbance Results for Various Temperatures
Time (secs) Ice Water Room Temperature Body Temperature
0 0.931 0.076 0.263
6 0.971 0.229 0.524
12 1.011 0.382 0.744
18 1.053 0.499 0.916
24 1.087 0.551 1.048
30 1.123 0.613 1.150
36 1.152 0.671 1.229
42 1.181 0.723 1.295
48 1.212 0.767 1.356
54 1.237 0.807 1.410
60 1.261 0.847 1.464


pH Reaction Rate (slope):
4°C .33/60
22°C 0.771/60
37°C 1.201/60


Experimental Setup for pH Experiment
Temperature Amount of Buffer Turnip Extract Substrate Mix Total
pH 2 buffer 2.2 ml 400 µl 400 µl 3.0 ml
pH 7 buffer 2.2 ml 400 µl 400 µl 3.0 ml
pH 10 buffer 2.2 ml 400 µl 400 µl 3.0 ml


Absorbance Results for Various pH Buffer Reactions
Time (secs) pH 2 pH 7 pH 10
0 0.044 0.268 0.000
6 0.043 0.359 0.000
12 0.042 0.443 0.000
18 0.042 0.521 0.000
24 0.042 0.591 0.000
30 0.044 0.651 0.000
36 0.044 0.707 0.000
42 0.046 0.763 0.000
48 0.045 0.812 0.000
54 0.046 0.859 0.000
60 0.046 0.904 0.000


pH Reaction Rate (slope):
pH 2 .416/60
pH 7 .636/60
pH 10 .000/60


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Discussion and Conclusion

  1. From the experiment, it can be found out that the optimum temperatures and the pH for the enzyme to function is similar to the normal body temperature and pH. Enzymes therefore have an optimum temperature of about 37 degrees Celsius and a pH level of about 7. These are the conditions commonly considered to be the Norman conditions and are generally referred to as the standard conditions for the enzyme activity. It is also important to note that drastic change in the ph and temperatures level can deform the enzyme and make then non functional.
  2. From the experiment conducted, it is possible to note that the ph effect on the enzymes activity confirms the results. Though the results in this particular experiment were not as drastic as expected, it shows the highest activity of the enzymes at the pH of 7 which is almost similar to the body pH. However, the results for the temperatures experiment did not give the results expected at all. The experiment concerning the temperature changes were far off the expected results. The wide deviations of the temperature results of the experiment from what is normally expected can be attributed to human errors which might have been incurred during the conduction of the experiments in the laboratory and in making the samples.


It cannot be disputed that enzymes are very important for all the body metabolic activities. These metabolic activities are very crucial in the body functionality and maintenance of the life. Given the right conditions of temperatures and the ph, enzymes reduce the activation barrier between them and the substrates. They thus come into contact with the substrate, and amicably change them but they remain unchanged. Provision of diverse conditions of temperature and pH however leads to the deformation of the shapes of the enzymes and as a result they would not be able to come in to close contact with the substrate to change them.

The gist concept of this experiment is to bring about the correlation between the enzyme activity and the changes in the enzyme environment. A close focus in placed on the particular effects of the pH and temperature influences on the enzyme activity. The fact that enzymes are found within the body of the living things, the effects of temperature and pH on the enzyme activity would reveal a close correlation of the possible effects the body is likely to undergo whenever it is exposed to the extreme and diverse cases of pH and environmental changes.

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