13. Oligomycin is a type of antibiotic that inhibits the proton channel (Fo subu
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13. Oligomycin is a type of antibiotic that inhibits the proton channel (Fo subunit) of ATP synthase. DNP is a known metabolic poison that uncouples oxidative phosphorylation by carrying protons across the inner mitochondrial membrane from the intermembrane space to the matrix. What is an expected result when both oligomycin and DNP are present in mitochondria? The actions of oligomycin and DNP cancel each other out. There is no net effect on regular oxidative phosphorylative ATP generation. ATP is produced as normal ATP is generated, but less than normal ATP is not produced, but a lot of heat is generated ATP is not produced and the proton pumps of the ETC stop pumping protons from the matrix to the intermembrane space A) B) C) D)Explanation / Answer
13. The correct answer is C) ATP is not produced, but a lot of heat is generated.
Explanation: According to the Chemiosmotic theory, as a high-energy electron is passed along the electron-transport chain, some of the released energy is used to drive three respiratory enzyme complexes [these enzyme complexes are NADH-coenzyme Q reductase(Complex I), Coenzyme Q-cytochrome c reductase(complex III) and cytochrome c oxidase(Complex IV)] that pump H+ out of the mitochondrial matrix into the intermitochondrial space. The resulting electrochemical proton gradient across the inner membrane drives H+ back through the ATP synthase which is a transmembrane protein complex that uses the energy of the H+ flow to synthesize ATP from ADP and Pi in the matrix.
ATP synthase consists of two parts: F0 component and F1 ATPase. An antibiotic oligomycin completely blocks ATP synthesis by blocking the flow of protons through F0 of ATP synthase.
2,4-dinitrophenol(DNP) is an example of an uncoupling agent. Uncoupling agents allow the oxidation of NADH and FADH2 and reduction of O2 to continue at high levels but do not permit ATP synthesis. Therefore, allow electron transport to proceed.
DNP is a lipophilic weak acid that can readily pass through membranes. In an anionic state, DNP picks up protons on the acidic side of the membrane, diffuse through, and release them on the alkaline side, thus dissipating the proton gradient and inhibiting ATP synthesis. The energy released by the oxidation of NADH in the presence of DNP is responsible for heat generation.
Therefore, The correct answer is C) ATP is not produced, but a lot of heat is generated.
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