Question

3. 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 Oligomycin Carbon monoxide 2,4-dinitrophenol (DNP) Rotenone Action Binds and blocks the proton channel in ATP synthase Inhibits cytochrome oxidase Binds protons and moves them down their electrochemical gradient Blocks electron transfer at NADH dehydrogenase a. Fill in the following table to predict and explain how these metabolic poisons affect different processes during cell respiration. Be brief! (30pt) Type of poison Effect on electron transport (increased, decreased, no effect) and why Effect on ATP synthesis (increased, decreased, no effect) and why Oligomycin Carbon monoxide Rotenone

3b) Would you expect rotenone to be more, less or equally poisonous as carbon monoxide? Explain you answer. (10pt)

Answer 1

1) Oligomycin- decreases the electron transport chain function as proton which are pass from matrix to intermembrane space is not coming back to matrix as ATP synthase is non functional due to oligomycin- no ATP synthesis as Fo subunit is not functional due to oligomycin- inhibitor

2) CO - decreases both electron transport chain as well as ATP synthesis proces as CO block cytochrome C oxidase and hence electron is blocked in between and hence no hydrogen is pumped out and hence no atp synthesis takes place.

3) DNP- leads no effect of electron transport chain as H+ conc keep on increasing by DNP but ATP synthesis is not formed or decreases it's iffect as H+ is not coming back to matrix.

4) rotenone leads to decrease effect of both electron transport chain as well as ATP synthesis process as rotenone is inhibitor of complex I of electron transport chain so no proton able to pass to intermembrane space and hence H+ will not able to come back through ATP synthase and hence no ATP synthesis.

This all shoes that electron transport chain and ATP synthesis both are coupled process.if one stop other also get stop except in case of DNP.

Hope it's clear..thanks