Understand the context of chemiosmosis: Chemiosmosis is the process by which ATP is synthesized using the energy from a proton gradient across a membrane, typically in mitochondria during cellular respiration or in chloroplasts during photosynthesis.
Identify the role of enzymes in chemiosmosis: Enzymes are biological catalysts that facilitate specific reactions. In chemiosmosis, the enzyme responsible for ATP synthesis is crucial for converting ADP and inorganic phosphate (Pi) into ATP.
Focus on ATP synthase: ATP synthase is a membrane-bound enzyme that uses the energy from the flow of protons (H⁺ ions) down their electrochemical gradient to catalyze the formation of ATP. This process occurs in the inner mitochondrial membrane or thylakoid membrane.
Eliminate incorrect options: Hexokinase is involved in glycolysis, not chemiosmosis. Cytochrome c oxidase is part of the electron transport chain but does not synthesize ATP. RuBisCO is involved in carbon fixation during photosynthesis, not ATP synthesis.
Conclude that ATP synthase is the correct enzyme: ATP synthase is specifically responsible for synthesizing ATP during chemiosmosis by utilizing the proton gradient created by the electron transport chain.