Here's why:
* Prokaryotes are single-celled organisms that lack a membrane-bound nucleus and other membrane-bound organelles. Their genetic material (DNA) is located in a region called the nucleoid, which is not enclosed by a membrane.
* Eukaryotic cells, on the other hand, have a true nucleus that contains their DNA and is separated from the cytoplasm by a nuclear membrane.
Examples of prokaryotes include bacteria and archaea.