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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]
Cells are broadly categorized into two types: eukaryotic cells, which possess a nucleus, and prokaryotic cells, which lack a nucleus but have a nucleoid region. Prokaryotes are single-celled organisms such as bacteria , whereas eukaryotes can be either single-celled, such as amoebae , or multicellular , such as some algae , plants , animals ...
While prokaryotes do not possess eukaryotic organelles, some do contain protein-shelled bacterial microcompartments, which are thought to act as primitive prokaryotic organelles; [1] and there is also evidence of other membrane-bounded structures. [2]
It was once thought that prokaryotic cells did not possess cytoskeletons, but advances in imaging technology and structure determination have shown the presence of filaments in these cells. [9] Homologues for all major cytoskeletal proteins in eukaryotes have been found in prokaryotes.
This is an accepted version of this page This is the latest accepted revision, reviewed on 23 December 2024. DNA molecule containing genetic material of a cell This article is about the DNA molecule. For the genetic algorithm, see Chromosome (genetic algorithm). Chromosome (10 7 - 10 10 bp) DNA Gene (10 3 - 10 6 bp) Function A chromosome and its packaged long strand of DNA unraveled. The DNA's ...
Although probable prokaryotic cell fossils date to almost 3.5 billion years ago, most prokaryotes do not have distinctive morphologies, and fossil shapes cannot be used to identify them as archaea. [58] Instead, chemical fossils of unique lipids are more informative because such compounds do not occur in other organisms. [59]
Although prokaryotic organisms do not possess a membrane-bound nucleus like eukaryotes, they do contain a nucleoid region in which the main chromosome is found. Extrachromosomal DNA exists in prokaryotes outside the nucleoid region as circular or linear plasmids.
Most prokaryotes, relying on circular chromosomes, accordingly do not possess telomeres. [12] A small fraction of bacterial chromosomes (such as those in Streptomyces , Agrobacterium , and Borrelia ), however, are linear and possess telomeres, which are very different from those of the eukaryotic chromosomes in structure and function.