Chemiosmosis and ATP synthase Transitional Reasoning Download PDF

Questions

1. 1.

   In an experiment using isolated mitochondria supplied with pyruvate and oxygen, researchers added a chemical compound that forms channels selectively permeable to protons across the inner mitochondrial membrane. Following the addition, oxygen consumption and electron transport continued at an elevated rate, but ATP production dropped immediately to zero. Based on these observations, which conclusion about the mechanism of ATP synthesis is best supported?

   • A) Electron transport synthesizes ATP through direct physical coupling rather than through an intermediate electrochemical gradient.
   • B) ATP synthase requires an intact proton gradient across the inner mitochondrial membrane to drive phosphorylation.
   • C) Protons must accumulate inside the mitochondrial matrix to provide the motive force that activates ATP synthase.
   • D) Oxygen acts as the immediate energy source that directly phosphorylates ADP during chemiosmosis.