On the Origin of Photosynthesis

World without photosynthesis, which has no greenery, no humble algae, none of the things that are nourish leaf munching organisms.  The complex multicellular life is the direct reaction of early photo-synthesizers’ actions. The oxygen released by these organisms helped the creation of ozone layer and made Earth congenial for both water and land-dwellers. Photosynthesis is one of the biggest milestones of evolution by changing the planetary environment forever and by steering the researches to the ways to harnessing light’s energy, the clues that can be found in delving into DNA sequences.  When the earliest solar-powered bacteria are scrutinized it can be said that these bacteria relied on different ingredients such as hydrogen sulfide and the photosynthetic machinery became more sophisticated day by day. Even though the molecular vestiges of the early events that remain in living organisms are blurred, today’s scientists are trying to illuminate the duration of photosynthesis’s evolution.

How organisms turn CO₂ and water into food? More than 100 organisms including chlorophyll team up to put light into work.  Plants and some organisms have the protein clusters photo-system I-II to use water as electron source. The electrical circuit starts with the light jump and it includes electrons flow from photosystems through protein channels to make ATP and NADPH, the energy-rich molecules which power the synthesis of the sugars that are needed.  Organisms use either oxygen or hydrogen sulfide as electron source. This difference of the e^- source may be evolved through the duplication of genes, but no one knows for sure.

To find the evolutionary path of photosystems, scientist first worked on the purple bacterium and created bacteriachlorophyll. They were not able to create –evolve- a strong oxidizer as Photosystem II so the reaction center wasn’t able to split water but it was enough to oxidize less possessive molecules such as hydrogen peroxide.  The scientists agree on the fact that shortly after life originated, the nonoxygenic photosynthesis arose before the oxygenic one. The disputes revolve around when organisms shifted to oxygenic one.

The great oxidation events (GOE) and the first hints of oxygenic systems are found by the fossil records. These hints could push the origin back around 600 million years. By the researches on the cynobacteria, scientist found those 3.2 billion years ago, microbes were using water to produce energy. During the search for traces of RuBisCO, a key photosynthetic enzyme is found. By these searches scientists conclude that oxygen-making photosynthesis began at least 2.9 billion years ago. One thing is for certain, however: Without this innovation, Earth would look a lot like Mars.