Final answer:
The energy for passive translocases' conformational changes originates from the proton electrochemical gradient generated by the ETC, which is harnessed through chemiosmosis to drive ATP production by ATP synthase.
Step-by-step explanation:
The energy for passive translocases' conformational changes in the inner mitochondrial membrane comes from the electrochemical gradient created by the electron transport chain (ETC).
This gradient is formed by the active pumping of hydrogen ions into the intermembrane space of the mitochondria, which results in the storage of potential energy.
The passage of these ions back across the membrane through ATP synthase is termed chemiosmosis, and the energy released during this process is used for the synthesis of ATP from ADP and inorganic phosphate (Pi).
In the context of photosynthesis, the energy from sunlight is captured by photosystems and used to pump hydrogen ions across the thylakoid membrane creating a similar gradient.
As with mitochondria, ATP production is then driven by the flow of hydrogen ions down their concentration gradient through ATP synthase, coupling the movement of protons with the phosphorylation of ADP to form ATP.
This process is essential for cellular energy needs and is facilitated by the potential energy stored in the proton gradient.