prokaryote

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Related to Prokaryotes: archaea, Archæa

prokaryote:

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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Prokaryote

 

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.

REFERENCE

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

IU. I. POLIANSKII

prokaryote

[prō′kar·ē‚ōt]
(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 ?
From this perspective, the genes responsible for aging--corresponding to the genes responsible for the generation of oxygen radicals--were already present in early prokaryotes. These genes were then passed on to the eukaryotes and have changed very little over evolutionary time.
The genetic machinery and structural organization of these two organisms merged to produce a new class of prokaryotes, called double membrane prokaryotes.
We did not identify any 16S rDNA sequences bearing similarity with gene sequences from any known Fe-oxidizing prokaryotes. This lack of sequence-based support for the presence of Fe-oxidizing microorganisms within environmental samples is not unusual in studies of microbial weathering in the deep sea.
Moreover, simulations of Mars' environment showed that prokaryotes, fungi, and lichens could survive, supporting the theory that life could have repeatedly been transferred between Earth and Mars.
Small RNAs in the prokaryotes: A growing list of diverse roles.
They are called prokaryotes, which means that they are microscopic, single-celled organisms.
Different parameters are actually applied to classify and analyze ncRNAs: (1) molecular length and structure [e.g., microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs)]; (2) mode of expression (housekeeping ncRNAs versus cell type-specific ncRNAs); (3) molecular mechanism of action (miRNAs are mechanically the best characterized ncRNAs); (4) organism where they are expressed (eukaryotes, prokaryotes, and Archaea).
They infect a wide spectrum of hosts ranging from prokaryotes (e.g., bacteria and archaea) to unicellular and multicellular eukaryotes, and therefore are considered as a controlling factor of both the abundance and the genetic diversity of populations (Brussaard, 2004; Suttle, 2007; Fischer et at., 2010).
"Horizontal genomics" is a new area of prokaryotic biology that investigates DNA sequences present in the chromosome that appear to have originated from other prokaryotes or eukaryotes.
Thus, unlike the later emerging and fossilizable animal hard parts [17], microbes in general, and prokaryotes in particular, have tiny body size and weak structures that are very difficult to fossilize and preserve [18].
In sections on fundamentals, methods, and applications, they consider such topics as the molecular taxonomy of environmental prokaryotes, the diversity of microbial extremophiles, microscopic techniques to assess prokaryotic molecular diversity in environmental samples, proteomics: principles and application in the microbiology of prokaryotes, potentials and challenges of microbial biofuels, and bioremediation.