Proton-Motive Force and ATP Synthesis

Flashcards focusing on key vocabulary and concepts related to the proton-motive force and ATP synthesis from the lecture notes.

Proton-Motive Force

The energy created by a proton gradient across the inner mitochondrial membrane that drives ATP synthesis.

ATP synthase

An enzyme that synthesizes ATP from ADP and inorganic phosphate, powered by the flow of protons through its rotor.

Chemiosmotic theory

The hypothesis proposed by Peter Mitchell stating that ATP synthesis is driven by a proton gradient across a membrane.

NADH-Q oxidoreductase

A complex in the electron transport chain that transfers electrons from NADH to coenzyme Q and pumps protons into the intermembrane space.

Malate-aspartate shuttle

A transport system that transfers electrons from cytosolic NADH into mitochondria, resulting in the regeneration of mitochondrial NADH.

Glycerol-3-phosphate shuttle

A method for transferring electrons from cytosolic NADH into the mitochondria, producing FADH2 instead of NADH.

ATP–ADP translocase (ANT)

A carrier protein that transports ADP into the mitochondrial matrix while exporting ATP out.

Proton gradient

The difference in proton concentration across a membrane, established by the electron transport chain.

Oxidative phosphorylation

The process where ATP is produced using the energy derived from the electron transport chain.

Acceptor control

The regulation of oxidative phosphorylation based on the availability of ADP, which is needed for ATP synthesis.

Reactive oxygen species (ROS)

Chemically reactive molecules that contain oxygen and are formed as by-products of the normal metabolism of oxygen.

Uncoupling proteins (UCPs)

Proteins in the mitochondrial membrane that dissipate the proton gradient, generating heat instead of ATP.

DNP (2,4-Dinitrophenol)

A chemical that uncouples oxidative phosphorylation, allowing electron transport to continue without ATP synthesis.

Efraim Racker

A scientist who contributed to the understanding of ATP synthase but initially viewed Peter Mitchell's chemiosmotic hypothesis skeptically.

Electrochemical gradient

The combined gradient of charge and concentration that drives the flow of protons through ATP synthase.

Substrate-level phosphorylation

A method of producing ATP by direct transfer of a phosphoryl group to ADP from another phosphorylated intermediate.

Proton-conducting unit

The component of ATP synthase that allows protons to flow through the c-ring, driving ATP synthesis.

Cyclic electron flow

A process in which electrons are recycled within the electron transport chain, generating an additional proton motive force.

Complex I

The first enzyme complex in the electron transport chain that accepts electrons from NADH.

Complex IV

The enzyme complex in the electron transport chain that transfers electrons to oxygen, the final electron acceptor.

Oxaloacetate

A four-carbon molecule that plays a key role in the citric acid cycle and is involved in the malate-aspartate shuttle.

Hyperpolarization

A state when the inside of the mitochondrial membrane becomes more negative compared to the outside due to proton pumping.

Respiratory chain

A series of protein complexes and other molecules that carry electrons through the inner mitochondrial membrane.

Endurance exercise

Physical activities which lead to adaptations in muscle cells, increasing mitochondrial density and ATP production.

Nobel Prize in Chemistry (1978)

Awarded to Peter Mitchell for his work in elucidating the chemiosmotic theory of ATP synthesis.

Hydrolysis of ATP

The process of breaking down ATP into ADP and inorganic phosphate, releasing energy for cellular processes.

Mitochondrial diseases

Disorders caused by dysfunctional mitochondria, often linked to mutations in mitochondrial DNA affecting oxidative phosphorylation.

Rotational catalysis

The mechanism whereby the rotation of the c-ring in ATP synthase facilitates ATP synthesis.

Heat shock proteins

Proteins that help stabilize and refold other proteins during stress conditions, potentially aiding mitochondrial function.

Brown adipose tissue (BAT)

A type of fat tissue that generates heat by uncoupling oxidative phosphorylation, rich in mitochondria.

Complex II

An enzyme complex in the electron transport chain that accepts electrons from succinate, bypassing Complex I.

Quinone (Q)

A mobile electron carrier in the electron transport chain that shuttles electrons between Complex I/II and Complex III.

Mitochondrial matrix

The space within the inner membrane of the mitochondria where the citric acid cycle and ATP synthesizing reactions occur.

Cristae

The inner membrane folds of mitochondria, increasing surface area for ATP synthesis.