Mitochondria Fumarate Lab Report

Introduction: The mitochondria are a vital organelle in eukaryotes, they are key in ATP production via the Electron Transport Chain. This chain is a series of 4 different protein complexes, which pump Hydrogen ions against their concentration gradient while obtaining electrons, and a complex called ATP Synthase, which is a turbine like complex which gains energy through the passage of Hydrogens, this energy is used to bind ADP and inorganic phosphate to form ATP. This chain can be easily disrupted with various enzymes, a few of which were tested in this lab. The purpose of the lab was to measure the reaction rate of succinate to fumarate, in the isolated mitochondria of cauliflower cells. This reaction is not visible to the naked eye, and thus an artificial electron acceptor DCIP was

When it was omitted from tube 7, the reaction slowed substantially. This indicated that substrate concentration and enzyme catalyzation are directly proportional, meaning that without the succinate there is no binding to the active site and thus no catalyzation of fumarate. But a small reaction with a velocity of -0.0068 (abs/min) still occurred, due to there being small traces of succinate present in mitochondria. This is significant because it shows that mitochondria may store, or at least hold some, succinate for use in the electron transport chain, but not enough to drive a strong or indefinitely long reaction. Based on all of the data collected, it is evident that as the concentration of succinate dehydrogenase is increased within a cell, the rate of the reaction where succinate is oxidized to fumarate increases (up to a point where enzyme conc. > substrate). This is the exact opposite of the effect of raising the concentration of malonate or sodium azide, which would decrease the rate of reaction because of the competition for active sites with succinate