Here's why:

* Prokaryotic Cells: Bacteria are classified as prokaryotes. This means they lack a membrane-bound nucleus.

* Single Compartment: Instead of a nucleus, their genetic material (DNA) is located in a region called the nucleoid. The nucleoid is not enclosed by a membrane, so it's considered a single compartment with the rest of the cell.

In contrast, eukaryotic cells, like those found in animals and plants, have a true nucleus where their DNA is housed.