What is the smallest unit of life that is classified as a prokaryotic organism?

The smallest unit of life classified as a prokaryotic organism is a bacterium. Prokaryotic organisms are characterized by the absence of a membrane-bound nucleus and other organelles, which distinguishes them from eukaryotic cells (like animal and plant cells). Bacteria are single-celled microorganisms that can exist independently or as part of a colony. They contain genetic material in the form of circular DNA located in a region called the nucleoid, and they usually reproduce asexually through a process called binary fission.

In contrast, viruses do not qualify as living organisms because they cannot carry out metabolic processes independently and require a host cell to replicate. Animal cells and plant cells are examples of eukaryotic cells, which have complex structures, including a definitive nucleus and various organelles, making them distinctly different from prokaryotic cells like bacteria. Understanding the defining characteristics of prokaryotes and eukaryotes helps clarify why a bacterium is the correct answer in this context.