Here's why:
* Eukaryotic cells have a true nucleus, which is a membrane-bound organelle that contains the cell's genetic material (DNA) in the form of chromosomes. This nucleus is the control center of the cell, regulating all cellular activities.
* Prokaryotic cells, on the other hand, lack a membrane-bound nucleus. Their DNA is located in a region called the nucleoid, which is not enclosed by a membrane.
In summary:
* Eukaryotes: Have a nucleus, which houses their DNA.
* Prokaryotes: Lack a nucleus, with their DNA located in the nucleoid.
This difference in cell structure is one of the defining characteristics that separates prokaryotes from eukaryotes.