Metabolic Reactions for Energy (geobiology)

Organisms, especially bacteria and archaea, get energy from a variety of chemical reactions. Photosynthesis and aerobic respiration are the two best known. Fermentation, sulfate reduction, methanogenesis, and methanotrophy are also important. Numerous other reactions can be evaluated using an "electron tower" of oxidation and reduction half reactions. In this video, I provide chemical reactions for some of the metabolisms and then discuss the electron tower. (Please forgive my 2 unbalanced equations! Fermentation of C6H12O6 produces 2 CO2 and 2 C2H6O plus energy. And it takes 2 O2 to oxidize one CH4. I added notes but didn't want to rerecord the video!)