The human body requires oxygen primarily for cellular respiration, where it acts as an electron and proton acceptor in the production of ATP, the energy currency of cells. While some organisms can utilize alternative compounds like sulfur, carbon dioxide, and nitrate under anaerobic conditions, these processes necessitate specialized proteins and significant physiological adaptations. The human respiratory system is specifically designed for oxygen intake and carbon dioxide expulsion, making it challenging to alter human genetics to enable breathing of toxic gases. Such modifications would require extensive changes to human physiology, as many poisons disrupt the respiratory chain, inhibiting electron transfer and proton translocation. Understanding energy metabolism, particularly the electron transport chain following the Krebs cycle, is crucial for exploring these complex biochemical processes.
