nietcellulaire

Nietcellulaire is a term used in biology to describe entities or structures that are not composed of cells. It is often applied to classify components that do not have cellular organization, such as certain infectious agents and extracellular structures. The etymology reflects its meaning: from Dutch niet meaning not, and cellulaire meaning cellular.

In practice, nietcellulaire is commonly contrasted with cellular life forms. It is related to the concept acellulaire in French or acellulair in Dutch, and to the English term acellular. Examples include viruses, viroids, and prions, which do not have cellular membranes, cytoplasm, or metabolism independent of a host. Viruses are genetic material encased in a protein coat; viroids consist solely of RNA; prions are misfolded proteins. Some non-cellular structures like extracellular matrices or certain virions not containing metabolic machinery are also described as non-cellular components.

Important nuance: while viruses and other non-cellular agents can propagate and cause disease, they are not considered living organisms by all definitions because they typically cannot reproduce or carry out metabolism outside a host cell. The term nietcellulaire thus sits at the boundary of biology, illustrating why discussions of life often distinguish cellular life from acellular agents.

See also: cell theory; acellular; viruses; prions; viroids; cellular organism.