Prokaryotae

Prokaryotae is a term historically used to classify organisms that lack a membrane-bound nucleus and other membrane-bound organelles. This classification was based on the fundamental cellular structure, distinguishing them from eukaryotes, which possess these internal compartments. The Prokaryotae kingdom was traditionally divided into two major domains: Bacteria and Archaea. Bacteria are ubiquitous and found in diverse environments, playing crucial roles in nutrient cycling and as pathogens. Archaea, initially discovered in extreme environments like hot springs and salt lakes, are also widespread and can be found in more moderate habitats as well.

The defining characteristic of prokaryotes is their cellular simplicity. Their genetic material, typically a single circular chromosome, resides in a region of the cytoplasm called the nucleoid. They reproduce asexually, primarily through binary fission. Despite their structural simplicity, prokaryotes exhibit remarkable metabolic diversity, utilizing a wide range of energy and carbon sources. Modern biological classification, based on molecular phylogeny, has largely superseded the formal Prokaryotae kingdom, recognizing Bacteria and Archaea as distinct domains of life. However, the term remains useful for describing the common cellular features shared by these two groups.