What defines a prokaryotic cell?

A prokaryotic cell is primarily defined by its lack of a nucleus, which is encapsulated in a membrane. This characteristic distinguishes prokaryotic cells from eukaryotic cells, which do have a defined nucleus that houses their genetic material. Additionally, prokaryotes also lack membrane-bound organelles, meaning that the internal structures of the cell are not compartmentalized within membranes, unlike in eukaryotic cells where organelles such as the mitochondria and endoplasmic reticulum are present.

While the presence of a cell wall is a common feature of many prokaryotic cells, it is not definitive since some prokaryotes do not have a cell wall. Furthermore, prokaryotic cells are typically smaller than eukaryotic cells, not larger. Therefore, the defining trait of lacking a membrane-bound nucleus along with the absence of membrane-bound organelles supports the definition of prokaryotic cells effectively.