| Summary: | The environment on pre-biotic Earth was characterised by a reducing atmosphere, consisting mainly of N2, C02, H20, H2S and 112, where the absence of oxygen led to high levels of ultraviolet light. In the "primordial soup" life likely evolved with sulfur playing a pivotal role [l] - a role that today is completely overshadowed by the evolution Of an oxidising oxygen- containing atmosphere based on photosynthesis of carbohydrates from C02 and H20. Evidence of the role of sulfur in the early history of life comes from the presence of sulfur in some key metabolic constituents, such as sulfur-iron clusters in cytochromes at the heart of many processes involving redox reactions, sulfur in two amino acids and the pivotal role of sulfur in the key metabolite acetyl-CoA which is paramount to all forms of life known [1, 2]. Even today, some remnants of the archaic nutrient cycles involving sulfur can be found in the world's more extreme aquatic environments: Thermal vents on the ocean floor [3], geothermal pools and anaerobic marine and limnic environments [2]. The environment on pre-biotic Earth was characterised by a reducing atmosphere, consisting mainly of N2, C02, H20, H2S and 112, where the absence of oxygen led to high levels of ultraviolet light. In the "primordial soup" life likely evolved with sulfur playing a pivotal role [l] - a role that today is completely overshadowed by the evolution Of an oxidising oxygen- containing atmosphere based on photosynthesis of carbohydrates from C02 and H20. Evidence of the role of sulfur in the early history of life comes from the presence of sulfur in some key metabolic constituents, such as sulfur-iron clusters in cytochromes at the heart of many processes involving redox reactions, sulfur in two amino acids and the pivotal role of sulfur in the key metabolite acetyl-CoA which is paramount to all forms of life known [1, 2]. Even today, some remnants of the archaic nutrient cycles involving sulfur can be found in the world's more extreme aquatic environments: Thermal vents on ...
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