5. The graph below shows the pH difference across the inner mitochondrial membra

Question

5. The graph below shows the pH difference across the inner mitochondrial membrane in a normal metabolically active cell. At the time indicated by the vertical arrow, a persor ingests cyanide. a. On the graph,draw what you would expet to see for the rest of the graphed line after cyanide ingestion. Time b. Explain why you would expect to see the results that you graphed. Becuse it prevens wer of elechrems How would your graph differ (if at all) after exposure to metformin? Dinitrophenol? Oligomycin? c. no

Explanation / Answer

5. a. There will be a sharp decline in pH after cyanide ingestion.

b. The poison cyanide blocks electron transport in the inner mitochondrial membrane which causes high rise in H+ conc thereby producing decrease in pH.

The close association of electron carriers with protein molecules helps in the process of oxidative phosphorylation. The movement of electrons from one enzyme complex to another is guided by the proteins along the respiratory chain. It results in pumping of H+ ion across the inner membrane i.e, from matrix to intermembrane space driven by electrons. This generates two results viz. generation of a pH gradient across the inner mitochondrial membrane with pH higher in the matrix than in cytosol, approx.7 and generation of a voltage gradient across inner mitochondrial membrane with negative charge inside and positive charge outside.

c. There will be no change in the graph. With oligomycin pH difference will collapse. With dinitrophenol the H+gradient is disrupted reducing ATP synthesis.

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