What structure is NOT found in prokaryotic cells?

Prokaryotic cells are characterized by their simplicity and lack of membrane-bound organelles. Among these structures, the nucleus is notably absent, which is a defining feature of prokaryotic cells. Instead of a nucleus, the genetic material in prokaryotes, typically in the form of a single circular DNA molecule, is located in a region called the nucleoid, which is not enclosed by a membrane.

In contrast, prokaryotic cells do possess other structures such as a cell wall, which provides support and protection, a plasma membrane that regulates the movement of substances in and out of the cell, and flagella, which are used for locomotion. These components are crucial for the survival and function of prokaryotic organisms, whereas the presence of a nucleus is a characteristic feature of eukaryotic cells. This distinction is fundamental in understanding the differences between these two major categories of life.