Here's why:

* Prokaryotic cells lack a nucleus and other membrane-bound organelles. Their DNA is located in a region called the nucleoid, which is not enclosed by a membrane. This means the DNA is directly within the cytoplasm.

* Eukaryotic cells, on the other hand, have their DNA contained within a nucleus, separated from the cytoplasm by a nuclear membrane.

While some eukaryotic organelles, like mitochondria and chloroplasts, contain their own DNA, this is considered an exception and is believed to be a remnant of their prokaryotic origins.