Electron Transport and Oxidative Phosphorylation

These flashcards cover essential vocabulary and concepts related to electron transport and oxidative phosphorylation in biochemistry.

Oxidative Phosphorylation

The metabolic pathway where cells use enzymes to oxidize nutrients, thereby releasing energy which is then used to produce ATP.

Electron Transport Chain

A series of protein complexes that transfer electrons from electron donors to electron acceptors via redox reactions while pumping protons to create a proton gradient.

Proton Gradient

A difference in proton concentrations across a membrane, which is used to drive the synthesis of ATP through ATP synthase.

P/O Ratio

The ratio of moles of inorganic phosphate (Pi) incorporated into ATP per mole of O2 reduced; typically estimated as 3 for NADH and 2 for FADH2.

Chemiosmotic Theory

A theory suggesting that ATP is generated in the mitochondria by the flow of protons back into the mitochondrial matrix through ATP synthase.

NADH

Nicotinamide adenine dinucleotide, a coenzyme that carries electrons to the electron transport chain and is a product of metabolic pathways like glycolysis.

FADH2

Flavin adenine dinucleotide reduced form which acts as an electron carrier in the electron transport chain, contributing less ATP than NADH due to bypassing complex I.

Complex I

NADH dehydrogenase, the first enzyme complex in the electron transport chain that oxidizes NADH and pumps protons into the intermembrane space.

ATP Synthase

An enzyme that synthesizes ATP from ADP and inorganic phosphate using the energy from the proton gradient.

Uncouplers

Compounds that disrupt the coupling between electron transport and ATP synthesis by allowing protons to flow back into the mitochondrial matrix without generating ATP.

Malate-Aspartate Shuttle

A mechanism that transfers electrons from cytosolic NADH into the mitochondria, effectively allowing it to contribute to ATP production.

Glycerol-3-Phosphate Shuttle

A pathway that transports reducing equivalents from cytosolic NADH into the mitochondrial electron transport chain, leading to the production of fewer ATP compared to malate-aspartate shuttle.

ΔG (Gibbs free energy)

A thermodynamic quantity that indicates the amount of energy in a system capable of doing work; used to measure energy changes in chemical reactions.

Exergonic Reaction

A reaction that releases energy, typically occurring spontaneously; common in redox reactions.

Equilibrium Constant (Keq)

A measure of the ratio of products to reactants at equilibrium; can indicate favorability of a reaction.

Oligomycin

An antibiotic that inhibits ATP synthase, blocking ATP production in mitochondria.

Thermogenin

A protein associated with non-shivering thermogenesis that allows for proton leakage in brown fat tissues, generating heat instead of ATP.

Half-Channel

A structural feature in ATP synthase involved in the transport of protons across the mitochondrial membrane by connecting the p-side to the n-side.

F0 Domain

The membrane-embedded region of ATP synthase responsible for proton transport.

F1 Domain

The soluble portion of ATP synthase that catalyzes the formation of ATP from ADP and inorganic phosphate.