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Oxidative Phosphorylation and Electron Transport

Problems

The Electron Transport Chain

Oxidative Phosphorylation

Problem : What two molecules are oxidized in the electron transport chain?

NADH and FADH are oxidized in the electron transport chain.

Problem : How is oxidation linked to electron transport?

An oxidation reaction involves the loss of electrons. When NADH and FADH are oxidized, they lose electrons. These electrons flow into the electron transport chain once they are released from NADH and FADH.

Problem : What is the destination of the electrons that flow through the electron transport chain?

The electrons in the electron transport chain ultimately flow to a molecule of oxygen, thereby reducing it to water.

Problem : What reaction of the citric acid cycle produces the FADH that is oxidized by complex II of the electron transport chain?

The reaction catalyzed by the enzyme succinate dehydrogenase, which converts succinate to fumarate produces a molecule of FADH.

Problem : Describe the nature of the electrochemical gradient established across the mitochondrial inner membrane as a result of electron transport.

As a result of electron transport, protons are pumped across the inner mitochondrial membrane out of the matrix into the intermembrane space. Because so many positive protons are pumped into the intermembrane space and the flow of electrons in inner membrane, a net positive charge is built up in the intermembrane space. A net negative charge is also built up in the matrix space.

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