Numerous trials were conducted on the varying factors affecting catalase reaction rates, focusing specifically on the concentration of hydrogen peroxide. The objective of the lab conducted was to study the several factors that affected the activity of enzymes. Before the trials had been started, it was predicted that the reaction rate would increase as the concentration of hydrogen peroxide decreased. The hypothesis stated that if the concentration of hydrogen peroxide decreased, then the reaction rate would increase because there would be less substance to lower the activation energy and increase the reaction rate (“How Does Catalase Break Down Hydrogen Peroxide?” 2002). In this experiment, the independent variable was the hydrogen peroxide concentration and the dependent variable was the reaction rate of the catalase. The experimental control group was the 100 percent hydrogen peroxide concentration mixed with tap water (0 percent). Throughout the experiment, the materials and yeast solution remained constant. In order for a chemical reaction to occur, activation energy is the energy required for it to start. Although many chemical reactions carry out the basic functions of life, some are too slow, or some have an activation energy too high to make them compatible with living organisms. To solve this naturally-occurring problem, cells make catalysts, which are substances that speed up the rate of the chemical reaction by lowering the required activation energy. Enzymes are proteins that are produced in the cell that act as a catalyst found in the body. Usually, they are specific to a certain chemical reaction, generally catalyzing only that one. In order for a chemical reaction to occur, the reactants have to collide with enough energy so that bonds already formed will break and form new ones (Miller & Levine, 2008, pg. 50-3). Enzymes can be reused to bind onto another substrate molecule and catalyze the reaction again, therefore, the process will continue until there are no more substrates to bind to. In rare situations, enzymes are not reusable due to denaturing- “an extreme temperature or pH change” (Chibata, Fukui, Wingard, 1982, pg. 384). If hydrogen peroxide is not immediately broken down or removed, it would kill cells due to the destruction of cell walls (Melina, 2011). 1. Hole punch filter paper. You will need 16 disks total to complete 16 trials.
2. Soak disks in yeast solution in petri dish.
3. Using the pipette, add 3mL of hydrogen peroxide solution to four wells.
4. Using the forceps, remove a disk from the yeast solution and place in the bottom of the well. Time how long it takes for the disk to reach the surface. Complete for all four trials and record data.
5. Wash the well plate, pipette, forceps, etc. thoroughly.
6. Repeat for other concentrations (DVHS Biology Department, 2018).
In order for the reaction rate of the catalase to be measured accurately, the filter paper circle was carefully placed in equal amounts of hydrogen peroxide the same way each time. Also, the timing done for each trial was carried out by the same person to ensure quality and accuracy. When the filter paper floated to the top, the timer was stopped immediately and data was collected in the data table. In this experiment, the constants were the: yeast solution, graduated cylinder, and tap water. The dependent variable was the reaction rate of the catalase, and the independent variable was the concentration of hydrogen peroxide. – When the filter paper was placed in the hydrogen peroxide, it started to fizz.
– As the concentration of hydrogen peroxide decreased, the reaction rate of the catalase increased.
The objective of this experiment was to study the several factors that affect the activity of enzymes. The hypothesis is supported and proposed that if the concentration of hydrogen peroxide decreased, the reaction rate would increase due to the lessening amount of catalase to lower the activation energy and decrease reaction rate. The data showed that when the concentration of hydrogen peroxide decreased, the reaction rate increased by an average of 15 percent. The greatest increase in reaction time occurred between the 50 percent and 75 percent hydrogen peroxide concentrations. Between the 75 percent and 100 percent concentrations, the reaction time decreased by an average of 3.45 seconds. According to the Worthington Biochemical Corporation (2018), “the rate of enzymatic reaction increases until a limited rate is reached.” Essentially, there is so much substrate present that all substrates are bound to an active site. Another factor that may have affected the results was temperature. Because the hydrogen peroxide acts as a catalase in this experiment, a decreasing quantity would keep the activation energy level the same and increase reaction rate. Enzymatic activity occurs in a limited range of temperatures compared to normal chemical reactions, therefore in order to get optimal results, the environment temperature should range between 37 and 40 degrees Celsius (Biology, 2012). The results of the experiment show that the reaction rate changes because of the direct relationship that exists between the concentration of the reactant and the reaction rate. Also, the reaction rate changes as the temperature changes because of the kinetic energy at the molecular level. As the temperature increases, the molecules often move faster whereas a lower temperature will slow down the movement of molecules. Additionally, pH is a varying factor of the solution. Solutions with a pH less than seven are considered acidic because there are more H+ions. Solutions with a pH greater than 7 are basic because there are more OH- ions (Miller & Levine, 2008, pg. 42-3). The following factors could have affected the results: observational error, environmental error, and instrumental error. For example, as the data was being collected, a researcher may have stopped the timer a second after the filter paper had rose. A future lab carried out with a natural enzyme and a more accurate saturation level could create a better understanding of the effect of hydrogen peroxide on catalase reaction rates.