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see MoneraMonera,
taxonomic kingdom that comprises the prokaryotes (bacteria and cyanobacteria). Prokaryotes are single-celled organisms that lack a membrane-bound nucleus and usually lack membrane-bound organelles (mitochondria, chloroplasts; see cell, in biology).
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an organism that does not have a typical cell nucleus and chromosomal apparatus. Prokaryotes include bacteria, blue-green algae, rickettsiae, and mycoplasms.

In the organic world, according to the latest classification system, prokaryotes are classified as a kingdom (Prokariota) or a superkingdom that is comparable to the kingdom or super-kingdom of eukaryotes. In prokaryotes, the physical substrate associated with the transmission and realization of hereditary information consists of a strand of deoxyribonucleic acid (DNA). The DNA usually has a ringlike shape and is localized more or less in the central part of the organism, which is called the nucleoid; the nucleoid is not separated by a membrane from the cytoplasm. Unlike the DNA in eukaryotes, the DNA in prokaryotes is usually not bound to histones (it does not form nucleohistone) and the functioning of genes is regulated through metabolites. Also, prokaryotes do not have mitochondria and complexly organized flagella.

Prokaryotes play a very important role in the cycle of matter in the biosphere. Blue-green algae were probably the first autotrophic organisms to appear on earth in the course of the evolution of life.


Peshkov, M. A. Tsitologiia bakterii. Moscow-Leningrad, 1955.



(cell and molecular biology)
A primitive nucleus, where the deoxyribonucleic acid-containing region lacks a limiting membrane.
Any cell containing such a nucleus, such as the bacteria and the blue-green algae.
References in periodicals archive ?
Prokaryotic cells have no nucleus, whereas eukaryotic cells do have a distinct nucleus that can undergo division to produce new cells.
Using one of the search engines on the Internet, such as Google, Yahoo!,, and MSN Live Search, find more information by searching for these words or phrases: plant cell structure, prokaryotic cells, eukaryotic cells, plant primary cell wall, plant secondary cell wall, membranes, organelles, mitochondrion, plastids, chloroplasts, endoplasmic reticulum, ribosomes, Golgi apparatus, and microtubules.
Humans consist of approximately 10% human cells and 90% prokaryotic cells, yet the idea of studying the varied relationships between eukaryotic hosts and prokaryotic symbionts is largely ignored in introductory biology classes.
G418 is one of the aminoglycoside antibiotics, which is toxic to both prokaryotic cells and eukaryotic cells.
The gill buds of these young clams are just beginning to form filaments, and subcellular inclusions resembling prokaryotic cells can be identified inside the unciliated cells located near the base of the filaments [ILLUSTRATION FOR FIGURE 3A OMITTED!.
Prokaryotic cells in the hydrothermal vent tube worm Riftia pachyptila Jones: possible chemoautotrophic symbionts.
At therapeutic doses, sub-lethal DNA damage has been reported after exposure to low-intensity red and infrared lasers in eukaryotic (5-7) and prokaryotic cells (8,9).
Prokaryotic cells are much smaller and simpler than eukaryotic cells.
The earliest eukaryotes evolved from symbioses between different prokaryotic cells, according to Margulis and others.
Ten of the 11 texts give the earliest date for prokaryotic cells as 3.5 bya.