Mitochondria play an important role in the functioning of cells. In this lab, students measure the oxygen consumption of mitochondrial extracts in the presence of different substrates, inhibitors and ADP to investigate the TCA cycle, electron transport and oxidative phosphorylation. They design experiments, calculate molar quantities and ratios, and interpret graphs of change in oxygen to deduce some of the basic properties of mitochondrial respiration. Seven substrates and six inhibitors can be used in any order or combination by the student, providing the flexibility for a number of different experiments.

The purpose of this laboratory is to:

• Demonstrate how studying the effects of intermediates in a reaction can be used to determine the steps in a metabolic pathway and the sequence of each enzymatic step in the pathway.

• Demonstrate how changes in substrates, products, and other reaction parameters can effect the reactions involved in the Krebs cycle, electron transport chain, and oxidative phosphorylation.

• Simulate the effects of substances that inhibit the reactions of aerobic cellular respiration.