Here's why:

* Prokaryotic cells are simple cells that lack a nucleus and other membrane-bound organelles. They have their genetic material (DNA) in a region called the nucleoid, but it's not enclosed within a membrane.

* Eukaryotic cells are more complex cells that have a nucleus, where their DNA is stored, and other membrane-bound organelles, like mitochondria and Golgi apparatus.

Bacteria are single-celled organisms that fall under the category of prokaryotes.