Final answer:
The intermembrane space within mitochondria accumulates hydrogen ions, creating a proton gradient that is fundamental for ATP production during cellular respiration.
Step-by-step explanation:
The intermembrane space is a crucial part of a mitochondrion, the powerhouse of eukaryotic cells, which is involved in cellular respiration. Specifically, the buildup occurring in the intermembrane space during cellular respiration is that of hydrogen ions (protons). These ions are pumped from the mitochondrial matrix into the intermembrane space by complexes I, III, and IV of the electron transport chain, creating a proton gradient.
This gradient is key to the production of adenosine triphosphate (ATP), which is the primary energy carrier in cells. The accumulation of hydrogen ions results in both a concentration gradient and an electrical gradient, due to their positive charge. The energy from this electrochemical gradient is harnessed by ATP synthase when hydrogen ions flow back into the matrix, driving the synthesis of ATP from adenosine diphosphate (ADP) and an inorganic phosphate.
In summary, the proton concentration in the intermembrane space serves an essential role in the mechanism of ATP formation, making it a focal point in the study of cellular metabolism and bioenergetics.