One glucose molecule burned fully with oxygen yields about 30 to 32 ATP; fermentation without oxygen yields just 2, losing more than nine tenths of the harvest. When oxygen runs out, respiration flips to anaerobic, the mitochondria fall quiet and only glycolysis keeps running out in the cytoplasm. Cyanide makes for a stranger case still: oxygen is plentiful but the last complex of the electron transport chain is blocked, so the cell cannot use any of it. The decisive place is the inner membrane, where proton pumps build the gradient that turns ATP synthase.
One glucose molecule burned fully with oxygen yields about 30 to 32 ATP; fermentation without oxygen yields just 2, losing more than nine tenths of the harvest. When oxygen runs out, respiration flips to anaerobic, the mitochondria fall quiet and only glycolysis keeps running out in the cytoplasm. Cyanide makes for a stranger case still: oxygen is plentiful but the last complex of the electron transport chain is blocked, so the cell cannot use any of it. The decisive place is the inner membrane, where proton pumps build the gradient that turns ATP synthase.
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