Photosynthetic evolving from

The amount of carbon dioxide in the atmosphere then has been estimated to be many times greater than today. This explains how the earth s climate was warm enough for liquid water and the life that evolved from it about 4 billion years ago. As life on earth evolved, the solar output increased and photosynthetic organisms used much of this carbon dioxide. 

Sulfate reducing bacteria were not antecedents of photosynthetic bacteria, but rather evolved from ancestral types which were photosynthetic bacteria. Although initially surprising, this evolntionary relationship is consistent with the idea that the accumulation of sulfate, the obligatory terminal electron acceptor for the sulfate reducing bacteria, was the resnlt of bacterial photosynthesis. 

Figure 12. Possible evolutionary interrelationships of aerobic prokaryotes evolving from photosynthetic bocateria (24).

The photosystems have structural features in common that suggest a common evolutionary origin. Similarities in organization and molecular structure to those of oxidative phosphorylation suggest that the photosynthetic apparatus evolved from an early energy-transduction system. 

Fig. 3 shows residual activity of hydrogenase in the pseudotransformants and the crude Extract from C. pasteurianum after transferred to aerobic conditions. Hydrogenase activity of the pseudotransformants under light conditions decreased more rapidly than under dark conditions, which was suspected to be due to 02 photosynthetically evolved. The clostridial hydrogenase activity in the pseudotransformants was rather stable than that in the crude extract. 

Why is it considered likely that the photosystems found in chloroplasts evolved from earlier photosynthetic organisms What is the minimum age for water-based, oxygen-producing photosynthesis ... 

From extensive study of plant genes, scientists figured out how C4 evolves from C3 (yes, present tense, because it s happening somewhere, right now). The pattern is the same as when multiple genes change together in discrete modules first a pump, then a shift in where electrons are moved, then a move of the main photosynthetic enzyme RuBisCO. These modules even look like computer sub-routines, and this new, complex process was assembled with steps so predictable that a computer could retrace them. No wonder it evolved so many times. 

Photosynthetic eukaryotes (eukaryotic algae, green plants) and heterotrophic eukaryotes (animals, fungi, protozoa) evolved from (a) common heterotrophic (amebo-flagellate) ancestor(s). 

Photosystem I reaction center, that functions on the reducing side of the electron transport chain, may have evolved from green photosynthetic bacteria (Olson 1970). Cyanobacteria which are the only free-living prokaryotes containing photosynthetic systems of the higher plants type, played a central role in the evolution of the complex (Padan 1979). 

The quantum yield of photosynthesis, the amount of product formed per equivalent of light input, has traditionally been expressed as the ratio of COg fixed or Og evolved per quantum absorbed. At each reaction center, one photon or quantum yields one electron. Interestingly, an overall stoichiometry of one translocated into the thylakoid vesicle for each photon has also been observed. Two photons per center would allow a pair of electrons to flow from HgO to NADP (Figure 22.12), resulting in the formation of 1 NADPH and Og. If one ATP were formed for every 3 H translocated during photosynthetic electron transport, 1 ATP would be synthesized. More appropriately, 4 hv per center (8 quanta total) would drive the evolution of 1 Og, the reduction of 2 NADP, and the phosphorylation of 2 ATP. 

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