What is a prokaryote?

Answer 1

Its a type of cell containig only plasmids.

Answer 2

Prokaryotes are by definition organisms without a nucleus containing the cell's chromosomes (pro - without, karyon - nucleus). They include all species of the domains bacteria and archaea.

However, the other key feature of prokaryotes si that they have co-transcriptional translation on their main chromosomes that is they translate messenger RNAs directly into proteins as they are being transcribed from the chromosomal DNA.

There has been some recent controversy amongst biologists about the term prokaryote with some claiming that the term should be abandoned.

The reason for this is that there are 3 domains of life. Eukaryota, Archaea and Bacteria. All three groups are highly genetically distinct, and archaea are actually more closely related to eukaryotes like humans than to bacteria. But despite that they are currently lumped with bacteria as prokaryotes, since they do not have a nucleus.

Answer 3

Prokaryotes (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. -otes; also spelled "procaryotes") are organisms without a cell nucleus (= karyon), or indeed any other membrane-bound organelles, in most cases unicellular (in rare cases, multicellular). This set of characteristics is distinct from eukaryotes (also spelled "eucaryotes"), organisms that have cell nuclei and may be variously unicellular or multicellular. The difference between the structure of prokaryotes and eukaryotes is so great that it is considered to be the most important distinction among groups of organisms. Most prokaryotes are bacteria, and the two terms are often treated as synonyms. However, Woese has proposed dividing prokaryotes into the Bacteria and Archaea (originally Eubacteria and Archaebacteria) because of the significant genetic differences between the two. This arrangement of Eukaryota (also called "Eukarya"), Bacteria, and Archaea is called the three-domain system. This replaces the two-empire system.

The cell structure of prokaryotes differs greatly from eukaryotes in many ways. The defining characteristic is, of course, the absence of a nucleus or nuclear envelope. Prokaryotes also were previously considered to lack cytoskeletons and do lack membrane-bound cell compartments such as vacuoles, endoplasmic reticulum/endoplasmic reticula, mitochondria and chloroplasts. In eukaryotes, the latter two perform various metabolic processes and are believed to have been derived from endosymbiotic bacteria. In prokaryotes similar processes occur across the cell membrane; endosymbionts are extremely rare. Prokaryotes also have cell walls, while some eukaryotes, particularly animals, do not. Both eukaryotes and prokaryotes have structures called ribosomes, which produce protein. Prokaryotes are usually much smaller than eukaryotic cells.

Prokaryotes have a single circular (only exceptionally linear, as in Borrelia burgdorferi or the Streptomyces) chromosome, contained within a region called the nucleoid rather than in a membrane-bound nucleus, but may also have various small circular pieces of DNA called plasmids spread throughout the cell. Reproduction is most often asexual, through binary fission, where the chromosome is duplicated and attaches to the cell membrane, and then the cell divides in two. However, they show a variety of parasexual processes where DNA is transferred between cells, such as transformation and transduction.

While prokaryotes are nearly always unicellular, some are capable of forming groups of cells called colonies. Unlike many eukaryotic multicellular organisms, each member of the colony is undifferentiated and capable of free-living. Individuals that make up such bacterial colonies most often still act independent of one another. Colonies are formed by organisms that remain attached following cell division, sometimes through the help of a secreted slime layer.

The prokaryotes are different to the eukaryote other than in the membrane bound organelles in that the DNA of the eukaryote is found in the nucleus while in the prokaryote there is only a single loop of DNA. Prokaryotic DNA also lacks the proteins found in eukaryotic DNA. Prokaryotes have a larger surface area to volume ratio. This gives the Prokaryotes a higher metabolic rate, a higher growth rate and thus a smaller generation time as compared to the Eukaryotes.

Recent research indicates that all prokaryotes actually do have cytoskeltons, albeit more primitive than those of eukaryotes, and at least some prokaryotes also contain intracellular structures which can be seen as primitive organelles. Membranous organelles (a. k .a. intracellular membranes) are known in some groups of prokaryotes, such as vacuoles or membrane systems devoted to special metabolic properties, e. g. photosynthesis or chemolithotrophy. Additionally, some species also contain protein-enclosed microcompartments mostly associated with special physiological properties (e. .g. carboxysomes or gas vacuoles).

Answer 4

A unicellular organism having cells lacking membrane-bound nuclei; bacteria are the prime example but also included are blue-green algae and actinomycetes and mycoplasma

Answer 5

prokaryotes are organisms that dont have a nuclear membrane, nuclear-bound cell organelles and have only one chromosome.
they have a very undefined nuclear region which has only nucleic acids.eg: bacteria.

Answer 6

a cell witout proper developed nucleus..

Answer 7

bacteria