What is chemiosmosis?

Chemiosmosis refers specifically to the process by which ATP is generated in mitochondria and chloroplasts, taking advantage of a proton (H+) electrochemical gradient. During cellular respiration, electrons are transported through a series of proteins in the electron transport chain, which creates an electrochemical gradient by moving protons from the mitochondrial matrix into the intermembrane space. This accumulation of protons creates potential energy, referred to as the proton motive force.

As protons flow back into the mitochondrial matrix through ATP synthase, a protein that acts as a channel and enzyme, the energy released is harnessed to synthesize ATP from ADP and inorganic phosphate. This mechanism of ATP generation is crucial for cellular energy supply and is a key component of oxidative phosphorylation.

In contrast, the other options describe different biological processes: the breakdown of glucose into pyruvate is glycolysis, converting acetyl-CoA into carbon dioxide occurs in the Krebs cycle, and the synthesis of glucose from carbon dioxide and water refers to photosynthesis. Therefore, A is the accurate representation of chemiosmosis within the context of cellular respiration.