Final answer:
ATP-synthase produces ATP in large quantities, utilizing the energy from a proton gradient through the process of chemiosmosis during oxidative phosphorylation in both cellular respiration and photosynthesis.
Step-by-step explanation:
Through an ATP-synthase, the molecule produced in large quantities is ATP (adenosine triphosphate). ATP synthase is a protein complex that uses the energy from a gradient of hydrogen ions (protons) crossing the mitochondrial membrane, a process known as chemiosmosis, to synthesize ATP from ADP (adenosine diphosphate) and inorganic phosphate (Pi).
This process occurs during cellular respiration, specifically in the step called oxidative phosphorylation, which takes place in the inner mitochondrial membrane of eukaryotic cells, or the thylakoid membrane of chloroplasts in plants. The formation of ATP through ATP synthase is an essential part of both photosynthesis and aerobic respiration.
During oxidative phosphorylation, the energy from the electrochemical proton gradient is harnessed by ATP synthase to convert ADP and Pi into ATP, the main energy currency of the cell. A similar process occurs during photosynthesis in the chloroplasts, but the proton gradient is established using light energy.