this is the temperature are bodies are and enzymes are designed to work best in this condition.
At low temperatures particles of reacting substances do not have much energy. However, when
the substances are heated, the particles gain energy. This causes them to move faster and collide
more often. The collisions have more energy, so more of them are successful. Therefore the rate
of reaction increases.
The more successful the collisions are the faster the reaction.
The same can be said for reactions controlled by enzymes, but because enzymes are proteins if
the temperature exceeds 50°C the enzyme will be denatured and will no longer work. For this
reason few cells can tolerate temperatures higher than approximately 45°C.
Enzymes are specific in the reactions they catalyse, much more so than inorganic Catalysts.
Normally, a given enzyme will Catalyse only one reaction, or type of reaction. The enzyme has
an active site that helps it to recognise its substrate in a very specific way. Just like a key only
fits into a specific lock, each enzyme has its own specific lock, each enzyme has its own specific
substrate. This is called the lock and key theory. The enzymes never actually get consumed in
the process, they just increase the rate of reactions.
When enzymes denature the heat starts to destroy their shape and structure. The shape of the
enzyme is so important to its working that any change in the shape of the molecules will make
them less effective or stop them working completely. Therefore I predict that by heating the
Hydrogen Peroxide, when it reacts with the enzyme the shape of the enzyme will be ruined due
to the high temperature.
So the higher the temperature of the Hydrogen Peroxide and Catalase solution, the less effective
the reaction will be.
THE EQUATION Hydrogen peroxide water + oxygen 2H2-------> 2H2O+ O2
We will be measuring three main factors:-
.Temperature-the optimum temperature of the enzyme.
.Oxygen-the amount released from the Hydrogen peroxide.
.Time- the duration of the reaction.
The room temperature may be a factor that will affect our results. Therefore we will have to try
our bests to insure the test is carried out under the same conditions. This includes the room
temperature.
To make it fair we will allow the reactions to have the same amount of time to occur. We will
change the TEMPERATURE of the Hydrogen Peroxide.
This is what our results table will look like…
Time (seconds)Temperature (oc)Volume of
cm3309503037783014193065603020503019486010406037152605070INVEST
IGATION EXPERIMENT
I am going to investigate how the enzyme, Catalase reacts at different temperatures. The
procedure for the experiment is as follows;
*Set up the apparatus; place water in the water bath, and fix the inverted measuring cylinder so
that the delivery tube connects it to the conical flask.
*Using a measuring cylinder, measure 20 ml of Hydrogen Peroxide.
*Measure 1cm3 of the enzyme (liver), Catalase and add it to the hydrogen peroxide solution in
a conical flask.
*Immediately place the bung on the conical flask, as the reaction would have already started.
* Set the timer for 30 seconds. Repeat the experiment three times, (for accuracy), using the
different selected temperatures.
*It is important that only the temperature is changed (of the hydrogen peroxide), since that is
what is being investigated.
RESULTS
Volume of H202Area of
LiverTimeTempWaterOxygen2563012404025630134141256301040402563023515125630
235656256302354542563031747425630297070256302972722563040858525630428656
25630418484256306090902563058949425630619292256308133256308033256308133I
predict that the enzyme will be totally denatured at 100°c and will no longer be active. We also
predict that the optimum temperature of this enzyme is 23°c (room temperature), the enzyme
may still react but not as much as it would with a lower temperature. Enzyme molecules can
take a little while to denature, even over 60°c. We predict that the enzyme may take up to 15-
30 minutes to completely denature at 60°c, by which time the reaction has already finished. To
help obtain the best possible results I will repeat each experiment three times and then find the
average set of data to plot on my graph. Our measurements will be very precise as we will carry
out the experiment as safely and fairly as possible. We are using accurate apparatus to allow us
to achieve this.
My perlim results show that enough gas is produced in 30s at all temp except 80 and above I
will use the range 30 for my experiment as 60 seconds is producing to much gas for the
measuring cylinder.
CONCLUSION
My results proved my prediction to be correct. The breakdown of Hydrogen Peroxide
accelerates as the temperature increases until the optimum temperature after which it begins to
slow down. Temperature influences the rate of enzyme activity. Usually a 10°c rise doubles the
rate of enzyme activity. This is only true up to an optimum temperature, however beyond this
point (usually 40°c) the 3D shape of the active site becomes distorted and the enzyme becomes
inactive.
Cooling or even freezing does not destroy enzymes, though it slows down their activity. From
studying the graph and our results table we can see the enzymes optimum temperature (23°c). It
was after 50°c where we could see a decrease in the enzymes activity. a rise in temperature
increases the rate of most chemical reactions and a fall in temperature will slow them down. In
many cases a rise in 10°C will double the rate of reaction in a cell. This is particle theory. We
investigated the temperature at which reactions occurred. We predicted that an increase in
temperature would result in an increase in kinetic energy. We were correct, since the speed of
particles increases, they should collide more often and therefore the speed of reaction increases.
The particles will also have more energy thereby speeding up the reaction even more. It has
been suggested that for every 10 degree rise in temperature, the speed of the reaction will
double.
At low temperatures particles of reacting substances do not have much energy. However, when
the substances are heated, the particles take in energy. This causes them to move faster and
collide more often. The collisions have more energy, so more of them are successful. Therefore
the rate of reaction increases.
The more successful the collisions are the faster the reaction.
The same can be said for reactions controlled by enzymes, but because enzymes are proteins if
the temperature exceeds 50°C the enzyme will be denatured and will no longer work. For this
reason few cells can tolerate temperatures higher than approximately 45°C.
Enzymes are specific in the reactions they catalyse, much more so than inorganic Catalysts.
Normally, a given enzyme will Catalyse only one reaction, or type of reaction. The enzyme has
an active site that helps it to recognise its substrate in a very specific way. Just like a key only
fits into a specific lock, each enzyme has its own specific lock, each enzyme has its own specific
substrate. This is called the lock and key theory. The enzymes never actually get consumed in
the process, they just increase the rate of reactions.
When enzymes denature the heat starts to destroy their shape and structure. The shape of the
enzyme is so important to its working that any change in the shape of the molecules will make
them less effective or stop them working completely. Therefore I predict that by heating the
Hydrogen Peroxide, when it reacts with the enzyme the shape of the enzyme will be ruined due
to the high temperature.
EVALUATION
Overall I would like to think our experiment went successfully. Everything went according to
plan. We followed out our safety instructions and did the experiment fairly and accurate as
possible. Therefore our results came out to be reliable and accurate. Due to using the equipment
safely and accurately this experiment has been successful. When measuring the amount of
Hydrogen Peroxide, we may have not measured the exact amount. We could have accidentally
measured 21ml, instead of 20ml. Luckily there were no spillages with the Hydrogen Peroxide or
Catalase, as we used the equipment safely and accurately. Also this experiment could have been
varied by using different equipment such as a volumetric syringe instead of collecting the gas
underwater or a temp probe in place of the thermometer. Catalyse is also found in potatoes so
the experiment could have been carried out using potatoes and not liver.
