Nichole Medeisis Section A23: David Cooper 2 March 2017 Team Members: Willow Schanz, Collyn Richards, Justin Peterson Question and Hypothesis Experiment 1: Question: Which one of the cell fractions of cauliflower had the largest concentration of mitochondria, identified by the enzymatic activity of SDH? Hypothesis: Our group predicted that Pellet 2 would contain the most mitochondria. We came to this conclusion because we know that the biggest and heaviest organelles are pushed down into the first pellet because of the slow spin of the centrifuge, leaving behind anything smaller. Additionally, we know that mitochondria may not be observed in big amounts in Pellet 3 because it is too large. …show more content…
We predicted this because we know that the farther the pH strays from neutral, the less enzymatic activity there is. When the pH becomes higher or lower than 7, or neutral, there is a decrease in enzyme activity and therefore a decrease in the activity of SDH. Even though we have the same amount of mitochondria, the enzyme itself is denaturing and so the reaction will run at a slower rate, causing less DCIP absorption to occur. With less DCIP absorption occurring, there will be less color change. This is because the solution becomes blue when DCIP is being oxidized and it becomes more clear when DCIP is being reduced. When the pH values stray from the neutral pH of 7, the less amount of reduction DCIP occurs and therefore the solutions would remain a blue …show more content…
We began to test of hypothesis by preparing another set of cuvettes with our Pellet 2 cell fraction of cauliflower because it had the greatest SDH activity. This time, we added assay buffers of different pH values. The values we used to test our hypothesis were pH values of 5.5, 6.0, 7.5, and 8.5. We tested 3 different pH values and kept our 4th pH with the value of 7.5 as the control, or blank, again. We again tested for absorbance at 600nm at times 0 minutes, 7 minutes, and 14 minutes. My group formed a hypothesis that the farther the pH was from neutral, or 7, the less the color of the solution would change. Figure 2A: Absorbance at 600 nm of solutions of different pH values over 7 minute intervals. Figure 2A shows the change in absorbance at 600 nm as we changed the pH of the solutions from acidic, to neutral for our control, to basic. We also measured the absorbances at 0 minutes, 7 minutes and 14 minutes. As seen in the graph, the solution with the pH of 8.5 went through the smallest change in absorbance at 600 nm with a change of 0.02. Also seen in the graph, our solution with the pH of 6.0 went through the largest change in absorbance at 600 nm. All of the pH values went through relatively equal changes in absorbance at 600