Aerobic Respiration
Textbook pages 106-107
Aerobic
• requires oxygen
– oxygen is required for the remainder of cellular
respiration
Krebs Cycle
• process where pyruvic acid is broken down into
CO2 in a series of energy-extracting reactions
• named after Hans Krebs
• also called the Citric Acid Cycle
Krebs Cycle
• occurs in mitochondria
• only produces 2 ATP molecules
– but produces a lot of high energy e– e- get stored on NADH and FADH2
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Krebs Cycle Reactants
pyruvic acid (also called pyruvate)
NAD+
FAD (similar to NAD+ - it is an electron carrier)
ADP
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Krebs Cycle Products
CO2
NADH
FADH2
ATP
38 ADP
+38 P
C6H12O6 + 6O2  6CO2 + 6H2O + energy
CELL
WORK
38 ATP
Electron Transport Chain
• uses the high-energy electrons from the Krebs
cycle to convert ADP into ATP
• occurs in inner mitochondria membranes
Electron Transport Chain
• series of proteins that pass electrons
• movement of e- = ENERGY
• causes H+ ions to cross the membrane
Electron Transport Chain
• last protein is an enzyme that combines
electrons with H+ and O2 to form H2O
• H+ ions pass through ATP synthase back into
the inner membrane by diffusion to produce
ATP
ATP Production of ETC
• produces a maximum of 34 ATP molecules per
molecule of glucose
– this number can vary and is still being studied
ETC Reactants
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NADH – from Krebs cycle
FADH2 – from Krebs cycle
ADP
O2
ETC Products
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NAD+
FAD
ATP
H 2O
Overall ATP Production
• 38 ATP molecules
• less than half of the total energy in glucose
– the rest is released as heat
• ATP supply in cells can get used up in a few
seconds
– must be constantly regenerated