Question

. In the lab, metabolic poisons can be used to study ATP synthesis and oxygen consumption. The action of several metabolic poisons is given in the table below

Poison	Action
Oligomycin	Binds and blocks the proton channel in ATP synthase
Carbon monoxide	Inhibits cytochrome oxidase
2,4-dinitrophenol (DNP)	Binds protons and moves them down their electrochemical gradient
Rotenone	Blocks electron transfer at NADH dehydrogenase

3b. Would you expect rotenone to be more, less or equally poisonous as carbon monoxide? Explain your answer.

Answer 1

Answer- If you block complex IV of ETC its mean electrons neither from NADH nor from FADH2 can be transferred to oxygen. But if we block only complex I electrons from FADH2 can be transferred to oxygen from succinate dehydrogenase, complex II.

So rotenone can inhibit electrons flow from NADH only not from FADH2. So if cells are treated with rotenone ETC will still occur with very slow rate. But if we treat the cells from CO it will completely block the ETC, there won't be any kind of electron flow, which will lead to a more severe consequence than rotenone.

So CO is more poisonous than rotenone