What is the primary characteristic of prokaryotes?

The primary characteristic of prokaryotes is that they lack membrane-bound organelles. This fundamental trait distinguishes prokaryotic cells from eukaryotic cells, which do contain a nucleus and various organelles, each surrounded by membranes. In prokaryotes, such as bacteria and archaea, the genetic material is organized in a nucleoid region rather than enclosed within a membrane-bound nucleus. Additionally, the absence of membrane-bound organelles means that processes like respiration and photosynthesis occur within the cytoplasm or across the cell membrane, rather than in specialized compartments like in eukaryotic cells.

Understanding this characteristic is crucial as it highlights the simpler structure of prokaryotes compared to eukaryotes, influencing their metabolic pathways and overall functions.