Final Answer:
As these electrons are continuously shuttled towards a molecule, there is an electron transport chain, so molecules that have a slightly higher affinity for electrons and excess energy are used to pump protons out of the cell across the membrane.
Step-by-step explanation:
In cellular respiration, the electron transport chain (ETC) plays a crucial role in generating ATP, the energy currency of cells. As electrons are shuttled through the ETC, the carriers in the chain have varying affinities for electrons. Molecules with a slightly higher affinity and excess energy, often oxygen in aerobic respiration, accept the electrons at the end of the chain. This acceptance of electrons leads to the formation of water molecules and contributes to the establishment of a proton gradient.
The movement of electrons through the ETC is coupled with the pumping of protons across the inner mitochondrial membrane (in eukaryotic cells) or the plasma membrane (in prokaryotic cells). This establishes an electrochemical gradient, as protons accumulate on one side of the membrane. The enzyme ATP synthase utilizes this gradient to generate ATP from ADP and inorganic phosphate, a process known as chemiosmosis. The energy released during the flow of protons back across the membrane through ATP synthase is harnessed to convert ADP into ATP.
This mechanism efficiently couples electron transport with ATP production, highlighting the significance of molecules with higher electron affinity in the final steps of cellular respiration.