Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles. They are divided into two kingdoms: Bacteria and Archaea. This division is based on significant differences in their genetic, biochemical, and structural characteristics.
Bacteria: These are the most common and widely studied prokaryotes. They have a cell wall made of peptidoglycan and can be found in almost every habitat on Earth. Bacteria play crucial roles in various ecological processes, including decomposition, nitrogen fixation, and as part of the human microbiome.
Archaea: Initially thought to be a type of bacteria, Archaea were later recognized as a distinct group due to their unique genetic and biochemical traits. They often inhabit extreme environments, such as hot springs, salt lakes, and deep-sea vents. Archaea have cell walls that lack peptidoglycan and possess unique membrane lipids.
The separation into two kingdoms reflects the evolutionary divergence between Bacteria and Archaea. This classification helps scientists better understand the diversity and evolutionary relationships among prokaryotes.