Electron Transport Chain and Oxidative Phosphorylation

• What is the first stage of catabolism?

  Acetyl group formation
• What is the second stage of catabolism?

  Citric Acid (Krebs) cycle
• What is the third stage of catabolism?

  Electron Transport Chain and Oxidative Phosphorylation
• What are the activated carriers of electrons for oxidation?

  • Electrons
  • O2 (ultimate electron acceptor)
  • Various electron carriers
• Name one coenzyme involved in biological oxidation.

  Nicotinamide adenine dinucleotide (NAD+)
• What is another coenzyme involved in biological oxidation?

  Nicotinamide adenine dinucleotide phosphate (NADP+)
• What is FAD+ an abbreviation for?

  Flavin adenine dinucleotide
• What is FMN an abbreviation for?

  Flavin mononucleotide
• What is Ubiquinone also known as?

  Coenzyme Q
• What role do cytochromes play in biological oxidation?

  They act as electron carriers
• What is the function of Coenzyme A (CoA)?

  It acts as a carrier for acyl groups
• What is the process of the Electron Transport Chain (ETC)?

  • Electrons and H+ are passed from NADH and FADH2
  • React with molecular O2 to produce H2O
  • Composed of protein complexes
• What is the reaction for NADH in the Electron Transport Chain?

  NADH + H+ → NAD+ + 2H+ + 2e-
• What is the reaction for FADH2 in the Electron Transport Chain?

  FADH2 → FAD + 2H+ + 2e-
• What is the reaction involving O2 in the Electron Transport Chain?

  O2 + 4e- + 4H+ → 2 H2O
• What is oxidative phosphorylation?

  Conversion of electron transfer potential to phosphate transfer potential
• How much ATP does NADH yield?

  2.5 ATPs
• How much ATP does FADH2 yield?

  1.5 ATPs
• Where is the location of the Electron Transport Chain (ETC)?

  Mitochondrion
• What happens to hydrogens in Complex I?

  They become protons and move back into the matrix
• What do electrons from NADH enter at Complex I?

  NADH coenzyme Q oxidoreductase
• What does Complex II do?

  Grabs electrons from a metabolite in the TCA cycle
• What does Complex III receive electrons from?

  UQH2 that diffuses from either CI or CII
• How are electrons moved through Complex III?

  One at a time through Fe-S and cytochromes
• What happens as electrons pass through Fe-S and cytochromes?

  2H+ are pumped across the membrane
• What is the final destination of electrons in Complex IV?

  Reduction of O2 to H2O
• How do electrons move through the ETC?

  By the overall negative ΔG
• What are the steps in the Electron Transport Chain?

  1. Electrons from NADH enter at Complex I
  2. Electrons from FADH2 enter at Complex II
  3. Electrons are transferred through complexes I-IV
  4. Protons are pumped across the membrane
  5. Final reduction of O2 to H2O
• What is the role of Flavin mononucleotide (FMN) in the ETC?

  It participates in electron transfer reactions
• What is the role of Iron-Sulfur Protein (Fe-SP) in the ETC?

  It transfers electrons from FMNH2 to UQ
• What happens to FMNH2 in the first step of the ETC?

  It is oxidized to FMN, releasing electrons
• What happens to Fe3+ in the second step of the ETC?

  It is reduced to Fe2+
• What is the final product of the Electron Transport Chain?

  Water (H2O)
• What are the key components of the Electron Transport Chain?

  • NADH and FADH2 as electron donors
  • Complexes I-IV
  • Ubiquinone (CoQ)
  • Cytochromes
  • Oxygen as the final electron acceptor
• What is the overall DG as electrons move through coenzymes and metal donors in the ETC?

  Overall NEGATIVE DG
• How do electrons move through the ETC?

  By the overall NEGATIVE DG
• What is the first step in the electron transport chain (ETC)?

  Flavin mononucleotide (FMN)
• What are the products of the oxidation of FMNH2 in the ETC?

  FMN, 2H+, and 2e-
• What is the second step in the electron transport chain (ETC)?

  Iron-Sulfur Protein (Fe-SP)
• What happens to Fe3+ SP in the second step of the ETC?

  It is reduced to Fe2+ SP