Question

Action of metabolic processes:

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

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

2.) Which metabolic poison described above will affect oxygen production in chloroplasts? Why other poisons described above do not affect oxygen production in chloroplasts? Explain your answers.

Answer 1

1. Rotenone is more poisonous than carbon monoxide because it works by interfering with the electron transport chain in mitochondria. Further inhibits the transfer of electrons from iron-sulfur centers in complex I to ubiquinone. This interferes with NADH during the production of usable cellular energy i.e. ATP. Complex I is unable to pass off its electron to CoQ, creating a back-up of electrons within the mitochondrial matrix.

These electrons are very important for futher processes and Oxidative phosphorylation which is very important step does not happen.

But in carbon monoxide, it binds to Cytochrome c oxidase which is the final electron acceptor of the mitochondrial electron transport chain, catalysing the oxidation of ferrocytochrome c by gaseous oxygen. COX activity gets partially prevented, while after some time its activity gets increased.​

2. Oligomycin.

Oligomycin bind and blocks the proton channel, the protons contribute to a proton gradient that is used to power synthesis of the energy-carrying molecule, ATP, and the oxygen is a byproduct.​

Oligomycin inhibits ATP synthase by blocking its proton channel, which is necessary for oxidative phosphorylation of ADP to ATP (energy production). The inhibition of ATP synthesis by oligomycin will significantly reduce electron flow through the electron transport chain; however, electron flow is not stopped completely due to a process known as proton leak or mitochondrial uncoupling But decreases the oxygen production more significantly than other poison mentioned above.