Just as were “invented,” somewhere between 1.6 bya and 600 mya a eukaryote ate a cyanobacterium and both survived, and that cyanobacterium became the ancestor of all chloroplasts, which is the photosynthetic organelle in all plants. As with similar previous events, it appears that it , and all plants are descended from that unique event. The invention of the chloroplast , which were the first plants. The first algae fossils are from about 1.2 bya. Most algae species are not called plants, as they are not descended from that instance when a eukaryote ate a cyanobacterium. The non-plant algae, such as , also have chloroplasts, from various “envelopment” events when algae chloroplasts were eaten and the grazers and chloroplasts survived. Below is the general outline of the tree of life today, in which bacteria and archaea combined to make eukaryotic cells, and in which the bacterium enveloped into a protist to make plants, and all complex life developed from protists. (Source: Wikimedia Commons)
Perhaps a few hundred million years after the first mitochondrion appeared, as the oceanic oxygen content, at least on the surface, increased as a result of oxygenic photosynthesis, those complex cells learned to use oxygen instead of hydrogen. It is difficult to overstate the importance of learning to use oxygen in respiration, called . Before the appearance of aerobic respiration, life generated energy via and . Because oxygen , aerobic respiration generates, on average, about per cycle as fermentation and anaerobic respiration do (although some types of anaerobic respiration can get ). The suite of complex life on Earth today would not have been possible without the energy provided by oxygenic respiration. At minimum, nothing could have flown, and any animal life that might have evolved would have never left the oceans because the atmosphere would not have been breathable. With the advent of aerobic respiration, became possible, as it is several times as efficient as anaerobic respiration and fermentation (about 40% as compared to less than 10%). Today’s food chains of several levels would be constrained to about two in the absence of oxygen. Some scientists have and oxygen and respiration in eukaryote evolution. is controversial.
As the tricothecenes are currently considered to be the most potent small- molecule inhibitors of protein synthesis in eukaryotic cells, the immunosuppression associated with exposure to these mycotoxins is likely to be directly or indirectly linked to inhibition of protein synthesis.