Electron flow down the electron-transport chain leads to:
A) the transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space.
B) the transport of protons across the inner mitochondrial membrane from the intermembrane space into the matrix.
C) the coupled synthesis of GTP.
D) a dangerous imbalance of K+ ions across the mitochondrial membrane.
E) None of the above.

Question

Quizplus · Accepted Answer

Electron flow down the electron-transport chain leads to the transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space through the enzyme complexes I, III, and IV. This creates a proton gradient that is used by ATP synthase to synthesize ATP in a process called oxidative phosphorylation. Choice B is incorrect because protons are actually transported from the intermembrane space into the matrix, not vice versa. Choice C is incorrect because GTP synthesis is coupled to the citric acid cycle, not electron transport. Choice D is incorrect because there is no mention of K+ ions in the electron-transport chain or mitochondrial membrane. Therefore, the correct answer is A.

Electron Flow Down the Electron-Transport Chain Leads To