Specific enzymes of the electron transport chain are unaffected by feedback inhibition, but the rate of electron transport through the pathway is affected by the levels of ADP and ATP. Greater ATP consumption by a cell is indicated by a buildup of ADP. As ATP usage decreases, the concentration of ADP decreases: ATP begins to build up in the cell.
The molecules that bind cellular respiration enzymes act as signals, giving the enzyme information about the cell's energy state. ATP and ADP are examples of molecules that regulate cellular respiration enzymes. ATP, for instance, is a "stop" signal: high levels mean that the cell has enough ATP and does not need to make more through cellular respiration.
This is a case of feedback inhibition in which a product feeds back to shut down its pathways.
