Module 5: Respiration

• what happens to pyruvate after glycolysis?

  oxidized to form acetyl-coA (NADH e- carrier)
• TCA cycle degrades acetyl-coa to produce CO2 and e-carriers (NADH and FADH)
• fat catabolism breaks down lipids to GAP via glycolysis and fatty acids via beta oxidation
• beta oxidation removes 2 carbons from fatty acid and produces acetyl-coa for TCA
• fat catabolism themes:

  • will reuse e- carrier (NAD + FAD)
  • product (acetyl-coa) is funneled into existing pathway
• electron trnasport systems are found in chemotrophs that grow by respiration
• electron transport systems use membrane gradient to separate charge, hold respiration components
• e- carries are organized from low to high reduction potential in the membrane
• e- carries in electron transport systems:

  • iron-sulfur proteins
  • chytochromes (heme factor)
  • quinone
  • NAD and FAD
• oxidative phosphorylation: O2 is terminal e- acceptor (aerobic respiration)
• what e- carriers are involved in converting e- energy to proton gradient?

  cytochrome aa3 and cytochrome b/c1
• cytochrome aa3 is a pump, gate opens with conformational changes
• how does proton gate open in chytochrome aa2?

  e- from cytochrome c reduce O2
• cytochrome b/c1 transfers e- between different types of carries
• how does cytochrome b/c1 transfer e-?

  reduced quinone donates e- to iron-sulfur factor, accepts protons across membrane from cytoplasm
• ATP synthase converts protons to ATP
• F0 compenent of ATP synthases is motor and proton movement
• F0 component:

  1. proton entry port in A subunit
  2. neutralizes C unit, rotate to exit port
  3. release proton
• F1 component (ATP Synthase): ATP synthesis at active site (beta subunit)
• F1 component:

  1. starts at loose conformation, binds ADP and phosphate
  2. 1/3 rotation of F0 changes to tight conformation, brings ADP and phosphate together to form ATP
  3. 1/3 rotation changes to open conformation, release ATP
  4. 1/3 rotation to reset
• organotrophs have orgnic e- donors
• lithotrophs had inorganic e- donors
• aerobic respiration: O2 is terminal e- acceptot
• anaerobic respiration terminal e- acceptors:

  • nitrate
  • sulfate
  • Fe3+
  • Co2
  • organic compounds