Lecture Notes: Eukaryotic Cells and Mitochondrial Function

Eukaryotic Cells and Organelles

Structure: Double-membraned organelles.
Function: Harness energy needed for cell growth and reproduction.
- Energy originates from reactions at the inner mitochondrial membrane.

Proton Gradient: Acts as a barrier to protons, maintaining a higher concentration in the intermembrane space than in the matrix.
F1F0 ATP Synthase: Utilizes the proton gradient to synthesize ATP, powering most cellular reactions.
- ATP synthesis is analogous to a power plant using flow to rotate a turbine.

No Gradient: Results in cessation of ATP synthase activity, leading to energy starvation and cell death.
Protein Complexes I-IV: Essential in establishing and maintaining the gradient.

Complex I-IV: Transfer electrons through coupled reactions, referred to as the electron transport chain.
Complex I:
- Electron Donor: NADH deposits electrons.
- Redox Centers: Electrons move from top to bottom due to affinity and distance. Energy released is used to pump protons.
- Coenzyme Q: Last redox center donates electrons here.
Complex II:
- Electron Donor: FADH2 receives electrons from succinate.
- Transfers electrons to coenzyme Q but does not pump protons.

Complex III:
- Receives electrons from coenzyme Q, passes them through redox centers to cytochrome c.
Complex IV:
- Final destination for electrons.
- Converts oxygen into water, incorporating protons and pumping additional ones into the intermembrane space.
- Oxygen is crucial as the final electron acceptor.

The electron transport chain makes the inner mitochondrial membrane a cellular power plant.
Oxygen is vital for ATP synthesis as the final electron acceptor.

For a deeper understanding, additional videos on mitochondrial reactions are recommended.