Prokaryotic cells are simple, single-celled organisms that lack a nucleus and other membrane-bound organelles. They are typically smaller than eukaryotic cells and have a more basic structure. The genetic material in prokaryotic cells is found in a region called the nucleoid, which is not enclosed by a membrane. Common examples of prokaryotic cells include bacteria and archaea. These cells have a cell membrane and a rigid cell wall that provides shape and protection. Prokaryotic cells reproduce quickly through a process called binary fission, allowing them to adapt rapidly to their environment. Despite their simplicity, they play crucial roles in ecosystems, such as decomposing organic matter and aiding in nutrient cycling.