Experiment 1: Questions and Hypothesis In this experiment, we were tasked to measure the amount of mitochondria in various cell fractions by looking for a biochemical marker within mitochondria called succinate dehydrogenase or SDH. This is an enzyme that catalyzes the conversion of succinate and FAD into fumarate and FADH2. The reduced electron carrier, FADH2, then carries the newly acquired electrons that it received in the Citric Acid Cycle and takes them to Ubiquinone in the mitochondrial electron transport chain (Leicht and McAllister, 2017). Measuring for the presence of this SDH can be tough so we have to get help from an artificial electron acceptor called DCIP. This acceptor is a blue color in its oxidized state, but upon the presence of SDH activity, the DCIP gets reduced and goes from blue to clear. This signals the transfer of electrons from SDHíFADH2 is present and thus means mitochondria must be present as well. However, in order for the electrons to go to DCIP we had to redirect the electrons from getting to …show more content…
To do this we prepared cuvettes with various different pH solutions. We used the assay buffer from experiment 1 as our positive control. This gave us a baseline because we already knew that at pH 7 we would likely see a high amount of SDH activity. Our various pH's we tested were 5, 5.5, 6, 6.5, positive control pH 7, 7.5, and 8. We mixed these with equal amounts of DCIP indicator, sodium azide, succinate, and cell fraction. The cell fraction that we used was P3 for all of them because we found this to have the highest SDH activity in experiment 1. We then put the same amount of P3 cell fraction in the solutions one at a time and as soon as we did this we measured the absorbance with the spec 20. We repeated this for each pH three different times. The intervals of these reading were 7 minutes apart each