Eukaryotic Cells and Mitochondria

Membrane-bound Organelles

• All eukaryotic cells have membrane-bound organelles.
• Mitochondria are double-membraned and essential for energy production.

Mitochondria Functions

• Inner mitochondrial membrane critical for proton concentration gradient.
• F1F0 ATP synthase uses the proton gradient for ATP synthesis.
• ATP provides energy for cell reactions.
• Mitochondria compare to power plants using flow to generate energy.

Electron Transport Chain (ETC)

Protein Complexes

• Four protein complexes are central: Complexes I, II, III, and IV.
• Complexes I, III, and IV pump protons; Complex II supports proton pumping.

Complex I

• Receives high-energy electrons from NADH.
• Electrons pass through redox centers, releasing energy.
• Pumps protons using released energy.
• Electrons passed to coenzyme Q.

Complex II

• Receives electrons from FADH2, similar to Complex I.
• Transfers electrons to coenzyme Q but does not pump protons.

Complex III

• Coenzyme Q transfers electrons to Complex III.
• Electrons move to cytochrome c and then to Complex IV.

Complex IV

• Final electron acceptor is oxygen, converting it to water.
• Strengthens proton gradient by incorporating protons into water and pumping them.

Overall Process

• Electron transfer chain stops without oxygen, halting ATP synthesis.
• Oxygen is essential as the final electron acceptor.
• Protein complexes densely packed on the mitochondrial membrane, acting as a power plant.