What characteristic defines prokaryotes?

Prokaryotes are defined by the absence of a nucleus and membrane-bound organelles. This characteristic sets them apart from eukaryotes, which do possess these features. In prokaryotic cells, the genetic material (DNA) is located in a region called the nucleoid, rather than within a defined nucleus. Additionally, prokaryotes do not have the complex organelles found in eukaryotic cells, such as mitochondria or endoplasmic reticulum, which are enclosed by membranes. This structural simplicity allows prokaryotes to reproduce quickly and adapt to various environments, showcasing their evolutionary success and diversity among living organisms.