Electron Transport Chain

Introduction

• The electron transport chain (ETC) is the final stage of the cellular respiration pathway, responsible for producing the majority of ATP molecules.
• It is a complex collection of proteins located on the inner mitochondrial membrane.

Key Processes in the Electron Transport Chain

1. Electron Donation

• NADH, a coenzyme, releases hydrogen ions and electrons into the electron transport chain.

2. Electron Transfer

• Electrons transfer their energy to proteins within the inner mitochondrial membrane.
• This energy transfer provides the necessary energy to pump hydrogen ions (protons) across the inner mitochondrial membrane.

3. Hydrogen Ion Movement

• As electrons move through the chain, hydrogen ions are pumped from the mitochondrial matrix into the intermembrane space, creating an electrochemical gradient.

4. ATP Synthesis

• The flow of hydrogen ions back across the inner mitochondrial membrane is facilitated by a protein called ATP synthase.
• This flow of hydrogen ions provides the energy needed for ATP synthesis.

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Electron Transport Chain

5. Oxygen as the Final Acceptor

• Oxygen serves as the final acceptor of hydrogen ions and electrons in the electron transport chain.
• It combines with these elements to form water.

6. ATP Production

• The electron transport chain is responsible for producing a significant amount of ATP molecules, the cell's energy currency.

Total ATP Production

• In total, the electron transport chain can produce up to 38 ATP molecules from one molecule of glucose during cellular respiration.

Alternative Metabolic Pathways

• If glucose is not available, the cell can use alternative respiratory substrates like starch, glycogen, proteins (amino acids), and fats.
• These substrates can be broken down into intermediates in glycolysis or the citric acid cycle, providing alternative metabolic pathways to generate ATP.

Summary

• The electron transport chain is the final stage of cellular respiration, located on the inner mitochondrial membrane.
• It plays a crucial role in ATP production, with electrons passing through proteins, pumping hydrogen ions, and facilitating ATP synthesis.
• Oxygen acts as the final acceptor of hydrogen ions and electrons, forming water.
• The ETC can produce up to 38 ATP molecules from one molecule of glucose.
• Alternative metabolic pathways can use various respiratory substrates to generate ATP when glucose is not available.