Aerobic Respiration
Actors:
C-C-C = pyruvate: 3 carbon molecule
CoA = co-enzyme A, a large enzyme that breaks pyruvate
C-C-CoA = acetyl CoA, two carbons joined to the enzyme
CO2 = carbon dioxide
NAD+, FAD, ADP = low energy molecules
NADH, FADH2, ATP = high energy molecule
H+ = hydrogen ion/proton
O2 = molecular oxygen
e- = electron
Transport:
Pyruvate is transported into the matrix of the mitochondrion.
Link reaction:
Pyruvate joins with co-enzyme A and is decarboxylated producing acetyl CoA and CO2.
This oxidation of pyruvate is coupled with the reduction of NAD+ into NADH and H+.
(CoA is an abbreviation, not a chemical formula)
C-C-C + CoA --> C-C-CoA + CO2
NAD+ + H --> NADH + H+
Krebs cycle:
1. Acetyl CoA bonds with a four carbon molecule in the matrix to produce a six carbon molecule and co-enzyme A.
2. The six carbon molecule is oxidized and decarboxylated to produce a five carbon molecule and a carbon dioxide.
This oxidation is coupled with the reduction of NAD+ into NADH and H+.
3. The five carbon molecule is oxidized and decarboxylated to produce a four carbon molecule and a carbon dioxide.
This oxidation is coupled with the reduction of NAD+ into NADH and H+.
4. The four carbon molecule is oxidized to reform the original four carbon molecule completing the cycle.
This oxidation is coupled with three reduction reactions: NAD+ into NADH and H+ ; FAD into FADH2 ; ADP + Pi into ATP.
1. C-C-CoA + C-C-C-C --> C-C-C-C-C-C + CoA
2. C-C-C-C-C-C --> C-C-C-C-C + CO2
NAD+ + H --> NADH + H+
3. C-C-C-C-C --> C-C-C-C + CO2
NAD+ + H --> NADH + H+
4. C-C-C-C --> C-C-C-C
NAD+ + H --> NADH + H+
FAD --> FADH2
ADP + Pi --> ATP
The products of the link reaction and the Krebs cycle from two pyruvate molecules are 6 carbon dioxide molecules and many high energy molecules (2ATP, 6NADH, and 2FADH2).
Krebs Cycle Animation (aka Citric Acid Cycle)
Krebs Cycle Song (Karaoke)
Oxidative phosphorylation: Electron Transport Chain Animation
The high energy molecules, NADH and FADH2, are oxidized (lose electrons) by proteins in the inner membrane. The proteins are reduced (gain electrons). A series of oxidation/reduction reactions occur in the inner membrane as the electrons are transported within the membrane; these reactions are coupled with the active pumping of hydrogen ions (H+) from the matrix to the intermembrane space. These proteins are called the electron transport chain. The electrons bond with molecular oxygen and hydrogen ions to form water at the end of the chain.
NADH --> NAD+ + e-
FADH2 --> FAD + 2e-
O2 + 4H+ + 4e- --> 2H2O
The high concentration of hydrogen ions in the intermembrane space creates a concentration gradient. The movement of hydrogen ions across the inner membrane, from high to low concentration, is called chemiosmosis. The movement from the chemiosmosis gives kinetic energy (energy of motion) to ATP synthase, an enzyme complex. ATP synthase uses the energy to bond ADP and Pi into ATP. ATP Synthase Animation
32ADP + 32Pi --> 32ATP
Net Production
2ATP (glycolysis) + 2ATP (Krebs cycle) + 32ATP (oxidative phosphorylation) = 36ATP
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