Cadena de transporte de electrones y Quimiosmosis (síntesis de ATP) [Fosforilación oxidativa]

Fosforilación Oxidativa: Stages and Energy Production

In this section, the discussion revolves around the process of oxidative phosphorylation, focusing on its stages and the energy produced during cellular respiration.

Chain of Electron Transport

• The oxidative phosphorylation consists of two closely linked components: the electron transport chain and chemiosmosis.

• The electron transport chain comprises complexes attached to the inner mitochondrial membrane, facilitating electron transfer through redox reactions.

• Components' arrangement in the electron transport chain: Complex 1 (NADH dehydrogenase), Complex 2 (Succinate dehydrogenase), Coenzyme Q, Complex 3 (Cytochrome c reductase), and Complex 4 (Cytochrome oxidase).

Functioning of Complexes

• Complex 1 receives electrons from NADH, mobilizing protons to create an electrochemical gradient.

• Complex 2 accepts electrons from FADH but does not pump protons like Complex 1.

• Electrons from both complexes are transferred to Coenzyme Q, leading to further electron transfers within the chain.

Electron Transfer and ATP Synthesis

This part delves into the continuation of electron transfer within the oxidative phosphorylation process and highlights ATP synthesis through chemiosmosis.

Electron Transfer Process

• After reaching Complex 3, electrons are passed to a mobile component called cytochrome c before being transferred to Complex 4.

• Complex 4 transfers electrons to oxygen molecules, aiding in water formation by combining oxygen atoms with protons.

Chemiosmosis for ATP Generation

• Proton movement by complexes contributes to an electrochemical gradient essential for ATP production via chemiosmosis.

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This section discusses the generation of the electrochemical gradient in mitochondria through proton movement facilitated by a protein called ATP synthase or complex V.

Generation of Electrochemical Gradient

• Protons move back to the mitochondrial matrix with the help of a protein known as ATP synthase or complex V.

• ATP synthase can be likened to a turbine in a hydroelectric plant, utilizing proton flow to synthesize ATP.

• Experimentally, it is observed that when four protons pass, ATP synthase forms one ATP molecule.

• Protons from the intermembrane space return to the matrix through complexes I, III, and IV, leading to the formation of approximately 2 ATP molecules per NADH molecule.

New Section

This section delves into the electron transport chain's role in generating ATP through proton movement facilitated by various complexes.

Electron Transport Chain and Proton Movement

• Complex II transfers electrons but does not displace protons; however, Complex III displaces 4 protons and Complex IV displaces 2 protons.

• Each FADH molecule contributes to 1.5 ATP production during oxidative phosphorylation.

New Section

This part explores how glucose metabolism leads to significant ATP production through different stages like glycolysis and oxidative phosphorylation.

Glucose Metabolism for ATP Production

• Glucose breakdown results in approximately 35 total ATP molecules due to NADH entering the electron transport chain.

• Different cells exhibit varying efficiencies in transporting NADH electrons for ATP synthesis, affecting overall energy yield.

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The discussion focuses on calculating total ATP production from glucose metabolism considering different stages like glycolysis and Krebs cycle.

Total ATP Production Calculation

• Considering all steps involved in cellular respiration from glucose breakdown yields around 30–32 total ATP molecules.

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This segment outlines aerobic cellular respiration's three main stages: glycolysis, Krebs cycle, and oxidative phosphorylation involving electron transport chain activities.

Aerobic Cellular Respiration Stages