Electron Transport Chain (ETC)

Overview

• Location: Inner mitochondrial membrane.
• Function: Major source of energy in aerobic pathways.
• Structure: Consists of the outer and inner mitochondrial membranes, intermembrane space, and the matrix.

Mitochondrial Membranes

• Outer Membrane: Encloses the organelle.
• Inner Membrane: Contains four enzyme complexes and various cycles like the Krebs cycle and beta-oxidation.
• Intermembrane Space: Space between membranes where H+ ions are pumped to create a gradient.

Electron Transport Chain Mechanism

• NADH and FADH2: Produced in cycles like Krebs cycle and carry electrons to the ETC.
• Electron Flow: Electrons move through complexes I to IV, generating energy.
• Proton Pumping: Energy used to pump H+ ions into the intermembrane space, creating a high concentration (electrochemical gradient).
• ATP Synthase: H+ ions flow back into the matrix through ATP synthase, driving the conversion of ADP to ATP.

Enzyme Complexes

Complex I

• Name: NADH Dehydrogenase Complex (NADH Oxido Reductase).
• Structure: L-shaped with vertical and horizontal arms.
• Function: Removes hydrogen from NADH and transfers electrons further into the ETC.
• Components: Contains flavine mononucleotides and iron-sulfur compounds.

Complex II

• Name: Succinate Dehydrogenase Complex.
• Function: Oxidizes succinate to fumarate in the Krebs cycle, producing FADH2.
• Components: Contains iron-sulfur clusters.

Complex III

• Name: Cytochrome Reductase (Q Cytochrome C Oxido Reductase).
• Components: Contains cytochromes b, c1, and c.
• Function: Accepts electrons and transfers them to cytochrome c.

Complex IV

• Name: Cytochrome C Oxidase.
• Function: Receives electrons from cytochrome c and reduces oxygen to water.
• Components: Contains heme and copper.

Additional Components

• Coenzyme Q: Transfers electrons between complexes I and III.
• Cytochrome C: Transports electrons from complex III to IV.

Conclusion

• The ETC is crucial for ATP production through oxidative phosphorylation.
• Next steps include detailed studies of the mechanics and energy calculations in the ETC.

Recommendations

• Watch related videos on Krebs cycle, glycolysis, and beta-oxidation for better understanding.
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