The chemical 2,4 - dinitrophenol (DNP) is an\"uncoupler of oxidative phosphoryla

Question

  The chemical 2,4 - dinitrophenol (DNP) is an"uncoupler of oxidative phosphorylation". It is a lipidsoluble chemical, which causes the cytoplasmicmembrane to become "leaky" toward protons (H+).During incubation with DNP, E. coli will continue tooxidize glucose to CO2, but stop producing ATP byoxidative phyosphorylation.   In three to four sentencesdescribe what has happened to the E .coli and why it isno longer producing ATP by oxidative phosphorylation.Include whether or not you think the electrontransport chain is still operating; include your reasons?

Explanation / Answer

Oxidative phosphorylation in bacteria are less susceptible to DNP compared to eukaryotes. Relatively high concentrations of DNP is required to inhibit oxidative phosphorylation in bacteria. However, E.coli continued to produce CO2, but stopped ATP synthesis because oxidative phosphorylation is not inhibited by DNP. Instead, it is uncoupled to ATP synthesis. DNP acts as an ionophore and causes leakage of protons across the membrane, thereby dissipating the proton gradient. This collapses the proton motive force which is used to drive ATP synthesis.

Cells continue to produce CO2, electron transport chain is still operative, but the protons generated cannot be used to synthesize ATP.

Only uncoupling of electron transport to oxidative phosphorylation occurred, as a result, ATP is not synthesized, but electron tranport is not inhibited.

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