Lecture 8
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All living things derive and use energy by common mechanisms
Lecture Outline No. 8

Aerobic Respiration:

The Mitochondrion: "Bacteria-like organelles"
        Outer membrane, folded inner membrane, matrix and inter-membrane space.

Electron Transport Chain (ETC):  Inner membrane of the mitochondrion.
        Transport of electrons from NAD:H and FAD:H2 to O2
        Electron "bucket brigade": Flavine, Iron-Sulfur and Heme proteins.

Chemiosmotic Theory of ATP Synthesis.
        Protons pumped "Uphill" into the intermembrane space by the ETC.
        Creates a proton concentration battery. An energy storage process.
        Energy from "down-hill" return of protons into the matrix can do work.
        The "downhill" return of protons through ATP synthase makes ATP.
        Peter Mitchell, 1961, Nobel Prize in 1978.

Anaerobic "Respiration":

In some bacteria, the ETC’s transport electrons to inorganic substances:
        carbonate ® methane ; sulfate ® hydrogen sulfide
        nitrate ® nitrite ® nitrous oxide ® nitrogen

Fermentations:

In the absence of oxygen, the NADH can pass its electrons to an organic molecule
    Pyruvate + NAD:H ® Lactic Acid (Bacteria, Muscle).
           ß ® CO2
    Acetaldehyde + NAD:H ® Alcohol (Yeast: Beer, Ale, Wine, Mead)

Evolutionary Perspective

Glycolysis: Oldest bioenergetic mechanism in ancient bacteria.

Anaerobic "Respiration": Probably second oldest bioenergetic mechanism; developed before the development of oxygenic photosynthesis.

Aerobic "Respiration": Developed in bacteria after formation of oxygen atmosphere. Mitochondria developed from aerobic bacterial symbionts.