Which characteristic distinguishes prokaryotic cells from eukaryotic cells?

The defining characteristic that distinguishes prokaryotic cells from eukaryotic cells is the absence of a nucleus. Prokaryotic cells, which include bacteria and archaea, lack a membrane-bound nucleus. Instead, their genetic material is found in a region called the nucleoid, which is not enclosed by a membrane. This fundamental difference in cellular organization is a key trait that impacts not only the structure of the cells but also their functions and processes, such as cell division and genetic replication.

Eukaryotic cells, on the other hand, have a defined nucleus that houses their DNA and is surrounded by a nuclear membrane. This compartmentalization allows for more complex regulation of gene expression and cell functions. Other options, such as multicellular structure or presence of a complex organelle system, more commonly relate to eukaryotic organisms, while prokaryotes can be unicellular and possess simpler structures. High genetic diversity is a feature that can be found in both prokaryotic and eukaryotic organisms, so it does not serve as a distinguishing trait between them.