At this juncture, we must, once again, stress the importance of the links between viral and cellular evolution and the coherence of the emerging scenarios.
What makes the endosymbiosis in trypanosomatids a special model to study cellular evolution is the fact that each protozoan contains only one symbiotic bacterium, indicating that the host imposes tight control over the endosymbiont division.
The induced cells might serve as a platform to study cellular evolution at the molecular level.
In the rest of this article, we consider evolution of viruses in conjunction with these two central concepts of cellular evolution: i) the existence of an early non-cellular but confined stage in life's evolution, that probably encompassed LUCA, and ii) the origin of the eukaryotic cell as a result of fusion of an archaeon and a bacterium.
The coherence of these results on one hand justifies the usefulness of domain bigram networks as a computational framework for the study of cellular evolution, and on the other hand reveals, to a degree, the biological basis underlying evolutionary cycles.
Unfortunately, much of the molecular and cellular evolution that accompanied the transition from cyanobacterium to photosynthetic organelle is unclear.
The New South Wales curriculum explicitly applies the evolutionary paradigm to chemical and cellular evolution through to the evolution of multicellular organisms (Board of Studies New South Wales 2009).
None of the recent fascinating discoveries about the huge viral diversity and its undeniable role in cellular evolution actually challenge the basic essence of viruses: they are strict molecular parasites unable to transform energy and matter.
We also suggest that a large portion of the pathway to inosine 5'-monophosphate (IMP) in purines could have been involved in thiamine synthesis or its derivatives in early stages of cellular evolution, correlating with the fact that these molecules may have played an active role in the protein-RNA world.
Thus, the origin and the evolution of basic biosynthetic pathways represented a crucial step in cellular evolution, since it rendered the primordial cells less dependent on the external source of nutrients.
