An Investigation Into a Reaction Catalysed by a Protease
Aim.
To investigate the effect of temperature and the effectiveness of this
enzyme in breaking down the gelatine (protein) on the back of
photographic film.
Prediction
I predict that the effect of the temperature will be that the higher
the temperature the quicker the enzyme will break down the gelatine,
but the temperature will have to be an optimum temperature because if
it is too high, the enzyme will be denatured. If the temperature is
too low, the enzyme will not work and stay stable.
Increasing the temperature provides more heat energy. This increases
the kinetic energy and makes the enzyme molecules move faster. There
will be an increase in the number of collisions and this will increase
the rates of reaction.
If the temperature continues to increase beyond 40°c, the molecules
move even faster, but the structure of the enzyme molecules has so
much energy that the bonds break. The enzyme begins to lose its
globular shape, which effects the active site, and the enzyme becomes
denatured. Also, for every enzyme there is an optimum PH at which the
reaction it catalyses proceeds most rapidly. Many enzymes work within
a PH range of an about 5-9 and works most efficiently at neutral of PH
7, that is why I will be using water.
Equipment
*10 pieces of photographic film
*20ml of protease enzyme in each test tube
*Water baths (23°c, 40°c, 50°c, 60°c, and 70°c)
*Buffer (5ml in each test tube)
*Stop watch
*Distilled water
*10 boiling tubes
*Goggles
Safety
Wear goggles, wear a lab coat, wash your hands after experiment, make
sure cotton is thread through the photographic film to avoid
contamination.
Variables
*Temperature is kept constant and controlled
* The film size is the same throughout
*Range of temperatures is used
*Use of a buffer (chemical to maintain a constant PH)
Method
Firstly set up the water baths at the specific temperatures and leave
In the pH homeostasis lab, 6 experiments were conducted. The hypotheses were: If base is added to water then the pH will increase; If acid is added to water then the pH will decrease; If base is added to homogenate, then the pH will increase; If acid is added to homogenate, then the pH will decrease; If acid or base is added to buffer, then the pH will remain the same. After the experiments were conducted, the graphs were somewhat similar to the hypotheses.
The reaction for pH 5 went off scale at one hundred seconds; its reaction went faster than the other tested pH levels. At twenty seconds, the pH 9 reaction reached 0.244 absorbance, slowly increased, and then slightly dropped to 0.296 by the end of the reaction (Figure 3). The rate of absorbance for peroxidase with pH 9 was 0.0097, so peroxidase activity is least optimal at pH 9. The absorbance rate for pH 3 was 0.0866, and the rate for pH 7 was 0.1426. Because the rate of absorbance for pH 5 was 0.3493, it is the optimum pH level for peroxidase. Highly acidic and alkaline pH levels reduce activity. (Figure
neutralize 35ml of our base. Once we weighed out the KHP we then dissolved it
Abstract: Enzymes are catalysts therefore we can state that they work to start a reaction or speed it up. The chemical transformed due to the enzyme (catalase) is known as the substrate. In this lab the chemical used was hydrogen peroxide because it can be broken down by catalase. The substrate in this lab would be hydrogen peroxide and the enzymes used will be catalase which is found in both potatoes and liver. This substrate will fill the active sites on the enzyme and the reaction will vary based on the concentration of both and the different factors in the experiment. Students placed either liver or potatoes in test tubes with the substrate and observed them at different temperatures as well as with different concentrations of the substrate. Upon reviewing observations, it can be concluded that liver contains the greater amount of catalase as its rates of reaction were greater than that of the potato.
I decided to experiment with pHs within the range pH 2 to pH7, as I
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one gram of water by 1ºC. I chose to use water because it is safe,
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Initially, before any NaOH is added, the pH of H2C2O4 .2H2O is low because it contains mainly H3O+. The starting pH will, however, be higher for a weak acid, like H2C2O4 .2H2O, than for a strong acid. As NaOH is added, H3O+ is slowly used by OH- because of dissociation of NaOH. The analyte remains acidic but the pH starts to increase as more NaOH is added.
From looking at the results I can conclude that when the pH was 3 and
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in a test tube. I then placed this in a water bath of the required
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The ph scale can be used to determine how strong an acid is. One meaning the acid is very strong and six meaning the acid is very weak. Some examples of acids are in the table below
pH levels shows how acidic or basic a substance is. A substance that is neither acidic or basic is called neutral. pH levels are very important in measuring the acidity of something for scientists. The scale ranges from 0 to 14. A pH of 7 is neutral, a pH less than 7 is acidic, and a pH greater than 7 is basic. Sour and fruity candy are very acidic. Some sour candies reach very low pH levels, such as warhead sour spray, which has a pH of one p...