Unicellular eukaryotes evolution

Tubulins arose very early during the course of evolution of unicellular eukaryotes and provide the machinery for the equipartitioning of chromosomes in mitosis, cell locomotion, and the maintenance of cell shape. The primordial genes that coded for tubulins likely were few in number. As metazoan evolution progressed, natural selection processes conserved multiple and mutant tubulin genes in response to the requirements for differentiated cell types (Sullivan, 1988). 

LGT is not expected to be common among or play the same role in the evolution of multicellular plants and animals, especially those with sequestered germ lines, and there simply is no extensive data on LGT in unicellular eukaryotes. 

While in unicellular eukaryotes the mitochondria were shown to play a central role in cellular FeS cluster assembly, metazoan ISC machinery might not be exclusively localized to mitochondria. It has been found that key ISC components, including IscS, IscU, Nfu, and frataxin, are located in the cytosol and nucleus as well as in mitochondria, and their participation in de novo FeS cluster synthesis outside of mitochondria was suggested (Tong and Rouault 2000, 2006). It would be interesting to investigate at which step of eukaryote evolution the transfer of ISC machinery to other cell compartments occurred and to clarify its extramitochondrial function. 

Van Houten, J.L. (1990). Chemosensory transduction in unicellular eukaryotes, in Evolution of the First Nervous Systems (P.A.V. Anderson, ed.), pp. 343-356. Plenum Press, New York, USA. 

Eubacterium 3, 6 Euglena 19 Euglenophyta 20 Eukaryote(s), unicellular 18-22 Eukaryotic cells 11-15 definition of 2 iron uptake 839 structure 10 Evolution 9... 

An army, a crowd, a nation, or other human societies, can be very complex structures, but none of them is as complex as a single individual human being. And the same is true for all animal societies a beehive or an ant-hill, for example, is a far simpler system than any individual insect. And if it is true that individuals are more complex than their societies, then it could be that single eukaryotic cells are more complex than societies of eukaryotic cells, i.e. multicellular organisms. And this in turn would explain why unicellular evolution had to be so much longer than multicellular evolution. 

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