Now that we have discussed the events of
glycolysis and the citric acid
cycle, we are ready to explore the
electron transport chain and oxidative
phosphorylation, the last step
in cellular respiration. The first two rounds of
aerobic respiration have produced only 4 ATP
and a number of coenzymes. This final stage
marks the ATP payoff, in which the NADH and FADH produced in earlier phases
enter the inner membrane of the mitochondria where they are oxidized.
As a result of the oxidation of NADH and FADH2, electrons are released. These
electrons then pass through a series of four protein complexes called the
electron transport chain. The energy produced from the flow of electrons
drives oxidative phosphorylation in which ATP is synthesized via the
addition of phosphor (phosphorylation) to ADP.
Oxidative phosphorylation marks the final stage of aerobic cell respiration. We
have traced metabolism from food to glucose, through the citric acid cycle, and
we will now see where the bulk of the ATP we use as fuel comes from. We will
begin our discussion by reviewing some key features of the
mitochondria.
Next, we will discuss electron flow through the electron transport
chain and ATP synthesis
through oxidative
phosphorylation.
