Universal Ancestor

A phylogenetic term for organisms at or below the divergence or branching between progenotes—which have rudimentary translation machinery—and genotes—which have modern translation machinery; the division is based on the ‘evolutionary clock,’ by which organisms are classified according to the evolution of the ribosomal RNA molecule
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In particular, the project ELiTE aims to decipher two major and inter-related steps in early life evolution and the rise of biological complexity: the evolution of cyanobacteria, responsible for Earth oxygenation and ancestor of the chloroplast, influencing drastically the evolution of life and the planet Earth, and the evolution of the domain Eucarya since LECA (Last Eucaryotic Universal Ancestor).
Woese (60) proposed the concept of "the universal ancestor" to look at the rooting of the evolutionary tree.
The surprisingly large extent of gene swapping has researchers asking whether comparisons of genes indicate how closely related different microbes are and if such analyses can truly point the way back to a universal ancestor. Furthermore, some biologists now argue that gene-transfer events lead to new bacterial species and can help explain why some microbes are harmless while others cause disease.
It appears that, at the time that the universal ancestor of all life gave rise to the primary lineages, the aminoacyl-tRNA synthetases had not achieved as settled an evolutionary condition as is generally assumed.
The nature of the last universal ancestor and the root of the tree of life, still open questions.
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