In this lab we are using yeast and hydrogen peroxide. We are trying to demonstrate how enzymes work and under which conditions they work best. An enzyme is a globular protein that is responsible for most of the chemical activities of living organisms. Enzymes can be used over and over again. One enzyme can catalyze thousands of reactions every second. Almost every organism has its temperature and range in which it will survive and it is most likely that their enzymes will function the best in that range. If an enzyme is not in the right environment, it will unravel until it is no longer in its shape that it needs to be in to function. There are at least two known enzymes that are known to catalyze reactions. Catalase, which is found in animals and protists and the other one is peroxidase which is found in plants. In the lab we are using yeast to demonstrate enzymes and the hydrogen peroxide to demonstrate substrates. We are demonstrating how enzymes work upon their environmental surroundings. Also we are measuring the pressure of oxygen gas formed as H2O2 is destroyed. When the peroxide is destroyed, less of it is available to react and the O2 is produced at lower rates. When peroxide runs out, O2 is no longer produced. Lets get started!
In the lab we needed the following material below:
- computer
- vernier computer interface
- LoggerPro
- Vernier Gas Pressure Sensor
- 1-hole rubber stopper assembly
- 10mL beaker of water
- 3% H2O2
- 600 mL beaker
- Enzyme suspension
- Four 18 x 150 mm test tubes
- Ice
- pH buffers
- Test tube rack
- Thermometer
- Three dropper pipettes
Part 1
We connected the Gas Pressure Sensor into the computer and then connected the tube to it. We used three test tubes in the first test. 3 mL of 3% H2O2 and 3 mL of water to all three of the test tubes. Thirty drops of yeast were placed in test tube number 1. The rate (slope) it took for the lid to pop off (the pressure to rise) was 27.05. The second test tube contained 50 drops of yeast in it and the rate (slope) was 11.85. The third tube contained 70 drops of yeast in it and it's slope was 0.3737. In part one we came to the conclusion that the more yeast (enzymes), the less time it takes for the pressure to rise or in other words the more enzymes, the less time it takes for them to break up substrates. Changing the concentration of enzymes affects the rate of decomposition of H2O2 by increasing the rate at which it is destroyed. Down below is a graph of the three tests.
Tube one: 27.05
Tube two: 11.85
Tube three:0.3737
Part 2
In part two we connected the Gas Pressure Sensor into the computer once again and connected its tube to it. This time we used 4 test tubes that contained 3 mL of 3% H2O2 and 3 mL of water. We tested each tube at a diffrerent temperature. We tested it at room temperature, warm temperature, hot temperature, and ice cold temperature. In test tube number one which was room temperature, we added 30 drops of yeast. The room temperature was at 71*F and the rate (slope) it took for the lid to pop off (pressure to rise) was 28.73. The second text tube was placed in warm water at the temperature of 5*C. The rate (slope) at which it took for the lid to pop off (pressure to rise) was -16.86. The third test tube was placed in hot water at a temperature of 9 *C with a rate (slope) of 22.80. The fourth test tube was placed in ice with the temperature of 30 *F with a rate (sloope) of 26.91. In part two we came to the conclusion that enzymes activity are highest when the temperature is warmer and the acdtivity is at the lowest with cool temperature. Down below is a graph of the 4 tests.
Test 1: 28.73
Test 2: -16.86
Test 3: 22.80
Test 4: 26.91
Part 3
In part 3 we placed the Gas Pressure Sensor into the computer and connected its tube to it. This time we used three test tubes and added 3 mL of 3% H2O2 and 3 mL of each pH buffer to each test tube. In the first test tube we added pH 4 and the rate (slope) at which it took for the lid to pop off (pressure to rise) was 21.18. In test tube 2 we added pH 7 and got the rate (slope) of 20.29. In test tube three we added pH 10 and got the rate (slope) of 9.953. We came to the conlusion that the rate of enzymes is highest at is pH 10 and its lowest at pH 4. Down below is a graph of the 4 tests.
Test 1: 21.18
Test 2: 20.29
Test 3: 9.953
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