Period5.C3

 **Enzymatic Activity Lab Taylor McAree, Alan Thomas, and Katrina Donahue Introduction: The Enzymatic Activity Lab concerns the regulation of the rate of chemical reactions and the regulation of enzyme activity. Enzymes speed up the rate of a reaction by lowering the activation energy barrier. Catalase is an enzymatic protein in the liver that breaks down hydrogen peroxide, therefore it is a catalyst. Liver in a hydrogen peroxide solution causes the hydrogen peroxide the break down, creating oxygen in the beaker. The creation of oxygen can be demonstrated by placing a blown out splint into the beaker: the splint will relight because of the present oxygen. In this experiment, the effects of changing the pH in a mixture of liver and hydrogen peroxide will be observed in the efficiency of the catalase. **

If an acid or a base is added to hydrogen peroxide and liver, then the catalase will not function as efficiently as when just hydrogen peroxide is added to liver because the acid or base will change the pH to drastically thus inhibiting optimal functioning conditions.
 * Hypothesis**:


 * Materials:**
 * three 1 cubic cm liver squares
 * three 100 mL graduated cylinders
 * hydrogen peroxide
 * HCL (acid) 1mol sol.
 * base
 * three 125 mL flasks
 * gas pressure sensor
 * LabPro

1. Gather materials :
 * Procedure:**
 * three 1 cubic cm liver squares
 * three 100 mL graduated cylinders
 * hydrogen peroxide
 * HCL
 * base
 * three 125 mL flasks
 * gas pressure sensor
 * LabPro

2. Prepare three 1 cubic cm liver squares using a scalpel making clean cuts (do not mash, grind, or beat the samples). 3. Keep liver samples at same temperature and moisture. 4. Prepare three 100 mL graduated cylinders and label them hydrogen peroxide, hydrogen peroxide with base, and hydrogen peroxide with acid. 5. Add 10 mL of hydrogen peroxide to each graduated cylinder. 6. Add 5 mL of HCL to the graduated cylinder labeled hydrogen peroxide with acid. 7. Add 5 mL of base to the graduated cylinder labeled hydrogen peroxide with base. 8. Label three 125 mL flasks as hydrogen peroxide, hydrogen peroxide with acid, and hydrogen peroxide with base. 9. Prepare LabPro and connect necessary tubing and launch Logger Pro on the computer 10. Select one flask and place the liver square in. 11. Quickly attach the stopper to the top of the flask and attach gas pressure sensor. 12. Press collect on Logger Pro. 13. Select experiment then store latest run. 14. Repeat steps steps 11 and 12 for each flask. 15. Record results.

Independent variable: pH Dependent variable: Rate of catalyst Controlled variables: Amount of liver, temperature, and amount of hydrogen peroxide used ** What do your results tell you about how your variable affected catalase activity?Include specific data from the experiment. If an acid or a base is added to the liver and hydrogen peroxide mixture, the catalase activity decreases. The data shows that the pressure within the flask continues to increase with only hydrogen peroxide, meaning that oxygen is being produced. From 0 to 80 seconds the pressure rises from 103.69 kPa to 132.75 kPa. However in the mixtures where an acid or base is added, there is almost no change in pressure. There is no hydrogen peroxide being decomposed and no oxygen being produced. The acid solution remained at 98.47 kPa while the base solution only rose from 97.56 kPa to 99.94 kPa during the 80 seconds.
 * Data:
 * || **Hydrogen Peroxide Pressure kPa** || **Acid Pressure kPa** || **Base Pressure kPa** ||
 * **Time (s)** ||  ||   ||   ||
 * **0** || 103.69 || 98.47 || 97.56 ||
 * **5** || 109.31 || 98.47 || 98.35 ||
 * **10** || 112.94 || 98.47 || 98.52 ||
 * **15** || 115.49 || 98.47 || 98.69 ||
 * **20** || 117.65 || 98.47 || 98.87 ||
 * **25** || 119.64 || 98.47 || 99.04 ||
 * **30** || 121.45 || 98.47 || 99.21 ||
 * **35** || 123.16 || 98.47 || 99.26 ||
 * **40** || 124.86 || 98.47 || 99.43 ||
 * **45** || 126.33 || 98.47 || 99.49 ||
 * **50** || 127.75 || 98.47 || 99.55 ||
 * **55** || 128.94 || 98.47 || 99.60 ||
 * **60** || 129.97 || 98.47 || 99.66 ||
 * **65** || 130.82 || 98.47 || 99.72 ||
 * **70** || 131.61 || 98.47 || 99.77 ||
 * **75** || 132.29 || 98.47 || 99.83 ||
 * **80** || 132.75 || 98.47 || 99.89 ||
 * **85** || 96.20 || 98.47 || 99.94 ||
 * Analysis Questions:

What were some sources of error and how might they have affected your data? What changes would you make to your procedure or what changes did your peer editor suggest that you make? One source of error that occurred during our experiment was the release of pressure from the flask. At 85 seconds the stopper covering the flask was popped off releasing the pressure and resulting in a sudden decrease on the graph. Other sources of error may have occurred while starting the graph, if the collect button was not pressed at the same moment during each run, it may result in slight variations in the numbers. **Another source of error was the 1cm3 liver samples were not exactly 1cm3 but a little above or below. Catalase is located in a cell organelle called the peroxisome. What do you think is the function of the peroxisome? Explain your reasoning. ** Peroxisome is an organelle that contains catalase and other enzymes. The purpose of the peroxisomes in liver cells is to produce hydrogen peroxide through an oxidative process. This allows for the catalase to react with the synthesized hydrogen peroxide later in the cycle. Hydrogen peroxide needs to be synthesized because it is a simple anti-germicide that our body can easily form. In the liver toxins are stored after ingestion and partial digestion. These toxins need to be partially sterilized until they can be excreted which is why hydrogen peroxide is needed. However hydrogen peroxide in large quantities is toxic also so catalase is needed to break down hydrogen peroxide after it has been used. All of this happens within a liver cell and the catalase is produced in the peroxisome. As a cheese-maker, what conditions would you want to have in your cheese factory to ensure that catalase was working best? Why would you need to make sure that the temperature of the catalase never went about a certain temperature? **
 * 
 * 

This lab effectively demonstrated how optimal functioning conditions of enzymes is very important to the efficiency of the enzyme in the reaction. The effect of a pH change drastically changed the product(O2) of the catalase hydrogen peroxide reaction. The experiment showed that the optimal functioning conditions for pH are at a near neutral pH of just hydrogen peroxide. When the pH was modified by adding either the acid or base the quantity of the product was reduced.
 * Conclusion:**