Prediction gridDifficulty 4/5 · HardOlympiadQuestions & methodsArgumentation
Mitochondria in an oxygen electrode
Isolated rat liver mitochondria are placed in a sealed, stirred chamber with an oxygen electrode, in a buffer containing phosphate and plentiful O₂. The substrates glutamate and malate supply NADH inside the matrix. Actively phosphorylating mitochondria (with ADP present) are the baseline for most rows; for the rows marked as follow-ons, compare with the state immediately before the addition.
For each addition, predict the change in the rate of O₂ consumption and the rate of ATP synthesis.
ADP added to mitochondria that had used up all their ADP
O₂ consumptionATP synthesisOligomycin (blocks ATP synthase's proton channel), vs. baseline
O₂ consumptionATP synthesisDNP (a protonophore) added after oligomycin, vs. oligomycin alone
O₂ consumptionATP synthesisRotenone (blocks Complex I), vs. baseline
O₂ consumptionATP synthesisSuccinate added after rotenone, vs. rotenone alone
O₂ consumptionATP synthesisCyanide (blocks Complex IV), vs. baseline
O₂ consumptionATP synthesis
| Row | O₂ consumption | ATP synthesis |
|---|---|---|
| ADP added to mitochondria that had used up all their ADP | ||
| Oligomycin (blocks ATP synthase's proton channel), vs. baseline | ||
| DNP (a protonophore) added after oligomycin, vs. oligomycin alone | ||
| Rotenone (blocks Complex I), vs. baseline | ||
| Succinate added after rotenone, vs. rotenone alone | ||
| Cyanide (blocks Complex IV), vs. baseline |
Answer every part to submit.