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Eukaryotic cells, containing membrane-bound organelles with diverse functions, probably derived from prokaryotes engulfing each other via phagocytosis. (See Symbiogenesis and Endosymbiont). Bacterial viruses (bacteriophages) emerge before or soon after the divergence of the prokaryotic and eukaryotic lineages. [44]
The evolution of bacteria has progressed over billions of years since the Precambrian time with their first major divergence from the archaeal/eukaryotic lineage roughly 3.2-3.5 billion years ago. [1] [2] This was discovered through gene sequencing of bacterial nucleoids to reconstruct their phylogeny.
Diagram of a prokaryotic cell, a bacterium with a flagellum. A prokaryote (/ p r oʊ ˈ k ær i oʊ t,-ə t /; less commonly spelled procaryote) [1] is a single-celled organism whose cell lacks a nucleus and other membrane-bound organelles. [2]
The three-domain system adds a level of classification (the domains) "above" the kingdoms present in the previously used five- or six-kingdom systems.This classification system recognizes the fundamental divide between the two prokaryotic groups, insofar as Archaea appear to be more closely related to eukaryotes than they are to other prokaryotes – bacteria-like organisms with no cell nucleus.
Last eukaryotic common ancestor – Process of forming the first eukaryotic cell; Pre-cell – Hypothetical life before complete cells; Proto-metabolism – Chemical reactions which turn into modern metabolism; Timeline of the evolutionary history of life
A major step forward in the study of bacteria came in 1977 when Carl Woese recognised that archaea have a separate line of evolutionary descent from bacteria. [263] This new phylogenetic taxonomy depended on the sequencing of 16S ribosomal RNA and divided prokaryotes into two evolutionary domains, as part of the three-domain system. [5]
The eukaryotic cell seems to have evolved from a symbiotic community of prokaryotic cells. DNA-bearing organelles like mitochondria and chloroplasts are remnants of ancient symbiotic oxygen-breathing bacteria and cyanobacteria, respectively, where at least part of the rest of the cell may have been derived from an ancestral archaean prokaryote ...
Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory [2]) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. [3]