Chemiosmosis and ATP synthase Original Scenario-Based Practice

Questions

1. 1.

   While navigating the aqueous intermembrane space of a bustling muscle cell's mitochondrion, the microscopic exploration probe Aura-7 records a steep electrochemical proton gradient pressing against the inner membrane. The probe's sensors detect swarms of positively charged hydrogen ions channeling exclusively through a specialized rotary enzyme toward the mitochondrial matrix. As these ions traverse the channel, the enzyme's catalytic head rotates rapidly, driving the massive generation of energy-rich fuel molecules. Which statement correctly describes the chemiosmotic mechanism observed by the probe?

   • A) The rotary enzyme actively pumps hydrogen ions against their concentration gradient into the matrix by consuming stored chemical energy.
   • B) Electrons flowing directly through the central rotor channel bind to inorganic phosphate to assemble ATP in the intermembrane space.
   • C) Protons diffuse directly across the phospholipid bilayer, while the rotary enzyme acts solely as a structural anchor that stabilizes ADP molecules.
   • D) Protons flow passively down their electrochemical gradient from the intermembrane space into the matrix through ATP synthase, powering the phosphorylation of ADP to ATP.

Answers and step-by-step solutions appear after you finish the test.