# Eukaryotic cell

## Definition

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

NOTE: The body of one organism may contain a lot of other organisms, which may be endosymbionts or parasites. Thus, the cells in (as opposed to of) a eukaryotic organism need not all be eukaryotic. For instance, the human body (eukaryotic) contains large number of bacteria, which are unicellular and prokaryotic.

The key features of eukaryotic cells in contrast with prokaryotic 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 ${\displaystyle \!10-100\mu m}$ ${\displaystyle \!1-10\mu m}$
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.