Originally posted by Xtal_Phusion
Too little energy is generated through anoxygenic photosynthesis. By default, this leaves us MICROORGANISMS! Chlorobium, otherwise known as green sulfur bacterium would be a good example. Most likely, however chemical constraints (pressure, temp, desiccation, etc.) would require reliance on a type of metabolism called chemoautotrophy. On Earth, microbes called extremophiles are clustered in a domain of life called Archaea (not the same as regular bacteria or "Eubacteria"). It is generally accepted that these are among the most ancient forms of cellular life on Earth today. Metabolic processes in this group can be very bizarre. Methanogens generate methane gas from simple hydrocarbons (i.e., methanol, ethanol), others live at very high/low pH, others still live at hydrothermal vents on the ocean floor where temperatures reach 130C or more. The most unusual is a polyextremophile called Deinococcus radiodurans. This bug surivived exposure to space outside the shuttle in orbit, makes a habit out of living in cooling tanks with spent rods at nuclear power plants and contains multiple copies of genes on circular DNA that stacks like a lifesaver to facilitate repair of broken fragments! This is true science and even more incredible than most realize! If you want to talk about life on Mars, how about discussing bugs that metabolize hydrogen and live deep beneath the Martian soil? They may not even HAVE DNA in their genomes! Think about it! According to the RNA world hypothesis, RNA was used before DNA and protein (performs the functions of both biomolecules to a less efficient degree & is still needed for many intermediate steps). A few groups are even working on other possible genetic systems and those are PNA (peptide backbone), TNA (threose backbone) and GNA (glycerol). Shall I outline some thermodynamic equations to demonstrate the differences between oxygenic and anoxygenic photosynthesis?