Pilot Study Results:
To find out exactly what I needed and how much I would need of substances and equipment used during my investigation a pilot study was carried out.
Originally I had planned to do a similar investigation but using liver as an enzyme, but this experiment proved to be to violent of a reaction to be able to obtain any substantial results therefore I had to change my investigation.
I had previously carried out an investigation on enzyme concentration on rate of reaction so I am aware of what I needed for my investigation. Firstly I had planned to increase the concentration of hydrogen peroxide solution but this only resulted in slowing down the rate of reaction so I then decided to increase the amount of yeast suspension and the outcome was successful, more gas was produced. Also at first I had planned to measure the gas at 5-10 second intervals but this was to soon and the results did not vary in volume, they were to close to gain a decent reading for the reaction, so I increased the time to every 30 seconds and this allowed enough time for the oxygen gas to accumulate.
Pilot Results:
Using 5cm3 of Hydrogen peroxide Rate of reaction = 1
Yeast suspension at 2.5cm3 time
Final method:
I will take a basin to the sink and fill it to 1 inch from the top with water then take it over to the desk. I will then collect two clamp stands and place them on my desk. Then I will collect a clean test tube with an arm and connect it to the first clamp stand with the test tube arm in the basin of water, then I will get a measuring cylinder and place it gently into the basin of water so not to fill the cylinder with air bubbles, then turn it up side down with the mouth over the end of the test tube arm and attach it to the second clamp stand to hold it in place safely I will then put 100ml of yeast suspension into a clean beaker and label it with a permanent marker and 100ml of hydrogen peroxide into a second clean beaker and label it with a permanent marker as well. I will then pipette the required amount of yeast suspension into the syringe and put in into the test tube with an arm.
I will then pipette the required amount of hydrogen peroxide with a separate syringe and keep it held inside as I insert the syringe into the cork in the top of the test tube with an arm. I will then clear a space to keep my record sheet and stop clock. I will reset my stop clock to 0.00 and then press ‘start’ and the syringe containing the hydrogen peroxide, then tabulate the volume of air given off every 30 seconds until I have reached three minutes. I will repeat the same experiment three times, then I will change the concentration of yeast suspension and repeat it again until I have done five different concentration three times each.
Results
Yeast at 2.5cm3 and H2O2
Yeast concentration at 3.5cm3 and H2O2 at cm
Yeast concentration at 4.5cm3 and H2O2 at 5cm3
Yeast concentration at 5.5cm3 and H2O2 at 5cm3
Yeast concentration at 6.5cm3 and H2O2 at 5cm3
Conclusion
My results tell me that as I increase the concentration on the enyme the amount of oxygen given off buy the reaction with hydrogen peroxide increases at a steady rate.
The data shows that the reaction between enzyme and substrate is very slow when the amount of enzyme is less than that of the substrate, but if you have more enzyme than substrate the reaction takes place much faster. This is because as there is enxyme there is more surface area in order for it to react with all the substrate in one go, but when there is less enzyme it takes longer to react and reacts at a much slower rate due to less surface area.
Within a time span of 30 seconds the volume of gas given off increases from 4cm3, 5cm3, between 7cm3 and 5cm3, between 8cm and 4cm and between 8cm3 and 3 cm3. There were some anomalous results that are indicated on the tables (marked by an asterix) I only had one result that was consistant though out all three trials and that is marked with a red asterix.
Explanation of results
An enzyme is made up of globular proteins which consist of polypeptide chains. The enzyme (yeast) is the active site on which the reaction takes place, for a reaction to occur the substrate (hydroegen peroxide) needs to be able to fit into the active site, if this cannot happen then the enzyme is usless and will not work efficiently if at all.
