PHYS1160 Lecture Notes - Lecture 4: Great Oxygenation Event, Photosynthetic Reaction Centre, Stromatolite
Document Summary
This is an interesting question for which there is substantial debate. To date, there is no sound evidence supporting any of the theories regarding the early origins of photosynthesis. The earliest sign of this complex process is approximately 3. 2-3. 5 billion years ago within stromatolites (layered rock formations produced by cyanobacteria) and microfossils linked to phototrophs through inferences. The current consensus suggests that photosynthesis began not long after the origin of life. However, it was not the initial mode of metabolism and the earlier forms of photosynthesis likely did not produce oxygen as a by-product. [1] this aligns with the idea that the great oxidation event wherein free oxygen accumulated in the atmosphere did not occur until 2. 4 billion years ago. Between the first sign of photosynthetic bacteria and that of atmospheric oxygen, there is approximately 1. 1 billion years for transformation to occur. Reaction centre complex is paramount to the process of photosynthesis.
