Last nights (my time) live video session with Bruce Damer was very thought stimulating and he mentioned ribosomes which I am fond of but only know about per se at a very basic level

After the video session a tweet (below) on fossil DNA came out to replace the video window and even though this was not directly related to ribosomes, the slide on the cyanobacteria reminded me of the ticker tape mechanism of ribosomes reading mRNA. ¿The thought came to me then, did ribosomes evolve in a lower order type of prokaryote endosymbiosis?

There are different levels of symbiosis, the most ancestrally basic known as mitochondria and chloroplasts in eukaryotes which are thought to have evolved from erstwhile prokaryotes, There is also symbiosis of a higher order such of eukaryotes on eukaryotes such as the photosynthetic green sea slug Elysia cholorotica which uses algae to photosynthesize is a process called kleptoplasty and another one is lichens which are formed from the symbiotic relationships between fungi and algae. One last example is that of the photosynthetic marine flatworm Symsagittifera roscoffensis,

Coming back to ribosomes, they are minute particles consisting of RNA and associated proteins, found in large numbers in the cytoplasm of living cells and which bind messenger RNA and transfer RNA to synthesize polypeptides and proteins. I mentioned my idea on whether ribosomes in organisms could have evolved as the result of some sort of endosymbiosis to a Saganet member that had remained online after the video. He answered that there was such a thing as ribozymes which are RNA molecules capable of acting as an enzyme. So I concluded that if an organism evolved to incorporate another organism that replicated using ribozymes using ribozymes itself to replicate too, endosymbiosis might have been possible, leading to the evolution of ribosomes.  Satellite viruses (See link below) might be doing something like the latter

Literally a few minutes after that event a post which I coincidentally came about was made on Natalie Cabrols Facebook page called Planetary Landscapes on the green sea slug Elysia cholorotica. I’d messaged Planetary Landscapes through Facebook on Elysia cholorotica last January to see if they knew about it and might want it to make a post but on that occasion they did not reply. I was so glad to see the post that I repeated on it all the ideas that had just occurred to me on Saganet which I’d also contributed to the Tweet I mentioned above.

Like I mentioned before, I only know about ribosomes per se in very basic terms but it seems to have been a plausible theory of endosymbiosis in prokaryotes.

I have in fact taught on Elysia cholorotica in Powerpoint presentations I have given on plants to classes of children. I have also given classes in English and Spanish to children on cosmological evolution and how that leads to biological evolution. I’ve done that in state schools and private educational concerns in Gibraltar and Spain. At the end of the classes we ask the children to draw a picture or write some text, or both, on their take on evolution and we give them actual polished fossils as prizes to the best four or five. I import Moroccan fossils from England because even if Morocco is just a few kilometers away from Gibraltar, it costs 4 times less to do so. ¡Bless Darwin!

https://twitter.com/SETIInstitute/status/1168983761817624576

Satellite Viruses   https://en.wikipedia.org/wiki/Satellite_(biology)