The aim of this experiment is to determine the effects of varying temperatures on the enzyme Catalase. I will find out if and how temperature affects an enzyme's rate of reaction.

The enzyme-controlled reaction I am investigating is how temperature affects an enzyme’s rate of reaction with the substrate.  The temperature will be the only independent variable in my experiment.  Everything else will stay constant.

I must try my hardest to keep all of the factors apart from temperature the same throughout the experiment.  I will carry out each recording of results twice and then I can get an average result, which should be correct.  If I do not keep the other factors the same then my results will not be accurate.

I predict that the breakdown of Hydrogen Peroxide will be quicker when the temperature is increased until it exceeds 40°C. This is the Q10 law.  It states that for every 10oc rise in temperature, the rate of reaction will double, up to about 40oc, when the enzyme starts to be denatured. (www.google.com)

I predict that the enzymes optimum temperature is 23°C (room temperature). This is because a rise in temperature increases the rate of collisions and a fall in temperature will slow them down. I am going to investigate the temperature at which reactions occur. I predict an increase in temperature will result in an increase in kinetic energy. 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 (Q10 law, www.google.com)

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.  

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.

To increase the accuracy of my investigation, I will keep every factors except temperature constant.  I will also work slowly so that nothing is rushed, this way I should not make mistakes.  The room temperature may be a factor that will affect my 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.

I did a practice experiment and overall I would like to think that the experiment went well and as planned.  We collected some results and because we worked carefully they should be quite accurate.

These results show that 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.

By doing this practice experiment I found that the temperature does not stay constant while I time the oxygen released.  Next time I shall top up the beaker of water every 30 seconds and that way the temperature will stay relatively constant.

The aim of this experiment is to determine the effect of varying temperature of enzyme Catalase.

First of all I shall set up my apparatus:

·  Test Tube Rack

·  6 test tubes

·  Potato

·  Bore

·  Knife

·  Set of scales

·  Ruler

·  Two large beakers

·  Kettle

·  Bucket of ice

·  Stop watch

·  Hydrogen Peroxide

·  pH 5 solution

·  Thermometer

·  Delivery tube with a bung

·  Syringe with a measuring scale

·  Heat proof mat

·  Bunsen burner

·  Tripod

·  Wire Gauze

 

I shall bore the potato and weigh the samples into equal sections.  After this I shall clear away the excess potato and start to set up my apparatus as shown above.  Before starting the experiment I shall keep the test tube containing the pH and Hydrogen peroxide in the large beaker filled with the correct temperature, so that the hydrogen peroxide can adjust to the correct temperature.  After I have done this I shall quickly place my potato sample in the test tube and place the bung on top so as not to loose the O2.  This should now pass through the delivery tube and collect in the syringe.  I shall time the reaction for 4 minutes and take a reading of how much O2 has been released.  I will repeat this for all 4 temperatures, each time using a different sample of potato.  

It is important that I use the apparatus carefully, as safety will be an issue through out the whole experiment. I will wear goggles to protect our eyes. As we are using enzymes and Hydrogen Peroxide we need to be extra careful, ensuring they don’t come in contact with our eyes and skin. I also must be careful when using hot water, being careful not to burn me. Therefore through out the whole experiment we shall be very careful in our actions around the lab.

Austin Finnegan 3S