Kreb Cycle

Oxidative Phosphorylation

• The third and most energy-producing stage of cellular respiration after glycolysis and the citric acid cycle.
• Utilizes the NADH and FADH2 produced in the citric acid cycle.
• Occurs in the mitochondria, specifically the inner mitochondrial membrane.

Electron Transport Chain

• A series of protein complexes (I-IV) embedded in the inner mitochondrial membrane.
• Each complex contains non-protein components called prosthetic groups, like flavin mononucleotides and cytochromes.
• Ubiquinone (Coenzyme Q) is a small, hydrophobic molecule that moves within the membrane and participates in electron transport.
• Electrons from NADH are passed through the chain, moving from one component to another with increasing electron affinity.
• This process does not directly produce ATP, but a proton gradient is generated across the membrane.

Proton Gradient and Chemiosmosis

• Protons accumulate in the intermembrane space, creating a proton gradient.
• The gradient represents stored energy called the proton-motive force.
• Protons move back into the mitochondrial matrix through a protein complex called ATP synthase.
• This movement of protons is called chemiosmosis and powers the phosphorylation of ADP to ATP.

ATP Synthase

• A protein complex that synthesizes ATP.
• Contains a rotor-like component that spins as protons bind.
• This spinning mechanism drives the phosphorylation of ADP.

Energy Yield

• Oxidative phosphorylation produces around 26-28 ATP molecules from a single glucose molecule.
• This is the main source of cellular energy.

Summary of Cellular Respiration

• Glycolysis produces 2 ATP and pyruvate, which enters the citric acid cycle.
• The citric cycle generates 2 ATP, 6 NADH, and 2 FADH2.
• These electron carriers power the electron transport chain, leading to a significant ATP yield.

Mitochondria and Cellular Energy

• Mitochondria are the powerhouses of the cell, responsible for most of the energy needed for cellular processes.
• Different food sources, including proteins, fats, and carbohydrates, are broken down into intermediates that feed into the cellular respiration pathways.

Test your understanding of oxidative phosphorylation, the final stage of cellular respiration. This quiz covers the electron transport chain, the role of NADH and FADH2, and the creation of the proton gradient in mitochondria. Challenge yourself and enhance your knowledge of these crucial biochemical processes.