Referring to the following figure predict the PO ratio for o

Referring to the following figure, predict the P/O ratio for oxidation of ascorbate by isolated mitochondria.

Succinate Rotenone and amytal FAD B-Hydroxybutyrate inhibit complex I e NAD FIMN Fe-S CoQ Ferricyanide Coupling site Complex Express your answer using one significant figure P/O ratio Submit My Answers Give Up PIO 2.5 Antimycin A cyt b Fe-S Coupling site Complex ill PIO 1.5 Ascorbate TMPD cyt C1 Exogenous cytochrome c Cyanide, azide, and carbon monoxide inhibit complex IV by reaction with cytochrome a3 cyt a cyt a Ferricyanide Coupling site Complex IV

Solution

P/O ratio - 0.5

P/O ratio - the number of ATP made per oxygen atom reduced.

When Ascorbate is the electron source, only complex IV is involved. Ascorbate transfers electrons directly to Cytochrome C. Only 2 protons are pumped. This produces 0.5 ATP per Oxygen.