Prokaryotic cell

Definition

Prokaryotic cells are a certain cell type based on the organisms which house these cells, which are called prokaryotic organisms (in other words, all cells in prokaryotic organisms are prokaryotic cells, and all prokaryotic cells are cells of prokaryotic organisms). These are contrasted from eukaryotic cells. The cells of prokaryotic organisms, which may be in the archaea or bacteria domain.

All prokaryotic organisms are unicellular organisms, so the prokaryotic cell is the prokaryotic organism. In contrast, eukaryotic organisms include both unicellular and multicellular organisms.

The key features of prokaryotic cells in contrast with eukaryotic cells are given below:

Attribute	For eukaryotic cells	For prokaryotic cells
existence of membrane-bound organelles, i.e., clear-cut compartmentalization	Eukaryotic cells have membrane-bound organelles, and hence clear-cut intracellular compartmentalization.	Prokaryotic cells do not have membrane-bound organelles. Although different regions of the cell perform different functions, these are not clearly separated organelles.
existence of a membrane-bound nucleus	Eukaryotic cells have a nucleus bounded by a double membrane.	Prokaryotic cells have a nucleus-like region called a nucleoid but this does not have a membrane.
arrangement of DNA	DNA is arranged in one or more chromosomes, which are rod-shaped structures, inside the nucleus.	DNA is arranged in a single circle.
cell size (diameter)	In microns: $\!10-100\mu m$ $1\mu m=10^{-6}m$	$\!1-10\mu m$ $1\mu m=10^{-6}m$
cellularity of organism	eukaryotic organisms could be unicellular organisms or multicellular organisms	prokaryotic organisms are always unicellular organisms, though the cells may cluster and communicate with each other for some prokaryotic organisms.