Final answer:
The essential components of an electron transport system are protein complexes and electron carriers. Electrons from NADH and FADH2 are transferred through a series of redox reactions in the inner membrane of mitochondria (or plasma membrane of prokaryotes). This process generates an electrochemical gradient that is used to produce ATP.
Step-by-step explanation:
The essential components of an electron transport system (ETS) are protein complexes and electron carriers. In the ETS, electrons from NADH and FADH2 are transferred through a series of redox reactions, passing rapidly from one electron carrier to the next. The ETS is embedded in the inner membrane of mitochondria (or the plasma membrane of prokaryotes) and consists of four protein complexes (I-IV) and two mobile accessory electron carriers.
As electrons are transported down the ETS, they move from higher to lower energy states, releasing energy. This energy is used to shuttle hydrogen ions (H*) from the mitochondrial matrix or cytoplasmic membrane, across the membrane, into the intermembrane space. This creates an electrochemical gradient, which is subsequently used to generate ATP during a process called chemiosmosis.