Which characteristic defines prokaryotic cells?

Prokaryotic cells are defined primarily by their genetic structure, which includes having a single, circular chromosome made of DNA. This characteristic is fundamental to prokaryotes, distinguishing them from eukaryotic cells, which typically have multiple linear chromosomes housed within a membrane-bound nucleus. The circular DNA in prokaryotes is usually located in a region called the nucleoid, as these cells lack the compartmentalization found in eukaryotic cells.

This circular arrangement allows for simple and efficient replication processes, which is essential for the often rapid reproduction of prokaryotic organisms, such as bacteria. The simplicity of their genetic organization is a key factor in their ability to adapt and thrive in various environments.

The other options suggest characteristics associated with eukaryotic cells, such as the presence of multiple chromosomes, membrane-bound organelles, and linear DNA wrapped around histones. These features are not found in prokaryotic cells and underline the distinct differences between the two types of cells.