Concept 9.4: During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis

Flashcards from Concept 9.4 of Pearson's Campbell Biology, Twelfth Edition.

NADH and FADH₂

The two electron carriers produced during glycolysis and the citric acid cycle that account for most of the extracted energy from glucose

• These donate electrons to the electron transport chain, powering ATP synthesis

Inner mitochondrial membrane

The location of the molecules of the electron transport chain in eukaryotic cells, folded into cristae for greater surface area

• Mostly comprised of proteins as part of a multi-protein complex that accepts electrons

Plasma membrane

The location of the electron transport chain in prokaryotic cells

Cytochromes

Proteins with heme groups containing an iron atom

• Serves as one of the carrier molecules in the electron transport chain

Electron transport chain

The chain of molecules that passes on electrons from NADH and FADH₂ through proteins to gradually release free energy towards oxygen molecules

• Serves to make energy to pump H⁺ from the mitochondrial matrix to the intermembrane space to catalyze ATP synthesis

• Can also accept and release H⁺ to maintain the H⁺ gradient and couple reactions to ATP synthesis

ATP synthase

The protein pump that H⁺ moves across after being powered by electrons to move into the intermembrane space

• The movement of H⁺ down the concentration gradient onto this protein’s binding sites in a rotor causes a spin that catalyzes ADP phosphorylation

Chemiosmosis

The use of energy in a H⁺ gradient to drive cellular work

• Seen in oxidative phosphorylation where H⁺ atoms are moved into the intermembrane space by electrons then moved into an ATP synthase rotor, catalyzing phosphorylation

Proton-motive force

An H⁺ gradient with the capacity to do work

32

The approximate number of ATP molecules created as a result of cellular respiration, representing about 34% of the energy in a glucose molecule

• The rest is lost as heat