Stages of Aerobic Respiration:

Glycolysis (cytoplasm)

• Process
  • 2ATP used for Glucose -> Fructose 1,6 bisphosphate
  • Fructose splits into G3P and DHAP. DHAP -oxidized by NAD⁺-> G3P (NADH produced)
  • Both G3P -oxidized by NAD⁺-> P_i attached creating 1,3 bisphosphoglycerate
  • Last 4 steps -Substrate level Phosphorylation x2-> ADP + P_i = ATP
• Formula (net)
  • Glucose + 2 ADP + 2 Pi + 2 NAD⁺
  • 2 Pyruvates + 2 ATP + 2 NADH + 2 H⁺

          Note that there are 2 ATP used and 4 ATPs produced in total

• NOTE the 2 NADHs become FADH₂ and get shuttled (glycerol phosphate shuttle) to the matrix

Pyruvate Oxidation (mitochondria)

• Process
  • Pyruvates enter mitochondria through protein channel
  • CO₂ is removed from acetyl group (DECARBOXYLATION!)
  • -oxidized by NAD⁺-> 2 NADH and H⁺ produced
  • Sulfur containing CoA attaches to the acetate -> Acetyl CoA (2-C compound)
• Formula
  • 2 Pyruvate + 2 NAD⁺ + 2 CoA
  • 2 Acetyl CoA + 2 NADH + 2 H⁺ + 2 CO₂

  Each step happens twice per glucose! (2 pyruvates!)

Kreb's Cycle (mitochondria)

• Process
  • #1: Combines with Oxaloacetate -> Citrate
  • #3 and #4: isocitrate àdecarboxylation -oxidized by NAD⁺-> 2 CO₂ and NADH
  • #5: GDP -> GTP -Substrate level Phosphorylation (ADP + P_i => ATP)-> GDP
  • #6: FAD -> FADH₂
  • #8: NAD⁺ -oxidized-> NADH à OXALOACETATE!
• Formula
  • Oxaloacetate + acetyl CoA + ADP + P_i + 3 NAD⁺ + FAD
  • CoA + ATP + 3 NADH + 3H⁺ + FADH₂ + 2 CO₂ + Oxaloacetate

  X2 for all reactants and products per glucose molecule

Electron Transport Chain and Chemiosmosis (mitochondria)

• Process
  • So far 8 NADH and 4 FADH₂ molecules have been created
  • 6 proteins => NADH Hydrogenase, Ubiquinone, Cytrochrome b-c₁ Complex, Cytochrome c, Cytochrome Oxidase Complex.
  • At the end, 2e^- reduce H⁺ + ½ O₂ => H₂O
  • NADH -> NAD⁺ (loses 2e^-)

  goes to NADH Hydrogenase first

  pumps 3 protons to intermembrane space => 3 ATP (actual 2.5)

o   FADH₂ -> FAD (loses 2e^-)

  Goes to Ubiquinone first

  Pumps 2 protons to intermembrane space => 2 ATP (actual 1.5)

o   Each proton pumped into intermembrane space

  Creates an electrochemical gradient of H+ ions

  The protons pass through ATP Synthase (ATPase) -> release free energy which is used to produce ATP

• Formula
  • 8 NADH + 4 FADH₂ + 2 H⁺ + ½ O₂ + 36 ADP + 36 P_i
  • 8 NAD⁺ + 4 FAD + 1 H₂O + 36 ATP (30 ATP actual)

  Note the 6 ATP less between the theoretical and actual yield