Mitochondrial Function and ATP Synthesis Overview

Mitochondrial Structure and Function

  • Central to ATP synthesis in eukaryotic cells.

  • Electron transport chain (ETC) involves multiple complexes: Complex I (NADH), Complex II (FADH2), Complex III, Complex IV (cytochrome c oxidase).

Electron Transport Chain (ETC) Involvement

  • Transfers electrons from NADH and FADH2 to oxygen, creating a proton gradient.

  • Respiratory complexes translocate protons: I (4 protons), II (0 protons), III (4 protons), IV (2 protons).

Reactive Oxygen Species (ROS)

  • Produced from incomplete reduction of O2 during electron transport, leading to superoxide and hydrogen peroxide.

  • Positive roles: signaling, immune functions, and physiological regulation.

  • Negative roles: oxidative stress linked to diseases like cancer, cardiovascular, and neurodegenerative diseases.

Chemiosmotic Model

  • Link between electron transport and ATP synthesis via proton gradients.

  • Free energy from electron transport used to pump protons, creating an electrochemical gradient.

ATP Synthesis via Proton Gradient

  • NADH produces ~3 ATP, and FADH2 ~2 ATP through proton pumping.

  • Uncouplers disrupt electron transport and ATP synthesis by collapsing gradients.

Maximum Yield of Aerobic Respiration

  • Cellular respiration yield varies: 36-38 ATP per glucose.

  • Factors affecting yield: cytosolic NADH transport, energy use for other processes.

Efficiency of Aerobic Respiration

  • Energy conservation from glucose to ATP is ~52-55% efficient.