What characteristic do eukaryotic cells have that prokaryotic cells do not?

Eukaryotic cells are distinguished from prokaryotic cells primarily by the presence of a nucleus. The nucleus is a membrane-bound organelle that houses the cell's genetic material (DNA). This structure allows for more complex regulation of gene expression and cell function since the DNA is separated from the cytoplasm. In prokaryotic cells, such as bacteria, the genetic material is located in a region called the nucleoid, which is not surrounded by a membrane. This fundamental difference is a key factor in the complexity and diversity of eukaryotic organisms, which can be unicellular or multicellular, and supports a variety of life forms, including plants, animals, fungi, and protists. The presence of a nucleus is integral to the advanced cellular processes and organelle functions found in eukaryotic cells.