noun, plural: procaryotes
Any of the group of organisms primarily characterized by the lack of true nucleus and other membrane-bound cell compartments: such as mitochondria and chloroplasts, and by the possession of a single loop of stable chromosomal DNA in the nucleiod region and cytoplasmic structures, such as plasma membrane, vacuoles, primitive cytoskeleton, and ribosomes.
Procaryotes do not have a well-defined nucleus but a nucleoid region in their cytoplasm where their genetic material occurs generally as a single, circular molecule of DNA.
Procaryotes are usually small in size, therefore, have a large surface area to volume ratio. Thus, they have high metabolic rate and high growth rate. They generally reproduce asexually, which is by binary fission or budding.
Most of them are unicellular, others are capable of forming stable aggregate communities.
Procaryotes belong to Kingdom Monera. Examples of procaryotes are bacteria, archaea and cyanobacteria (blue-green algae).
Word origin: from the Old Greek pro-, before + karyon, nut or kernel, referring to the cell nucleus, + suffix -otos, pl. -otes;
Related forms: procaryotic (adjective).
See also: bacteria.