Nucleoid

Part of speech: noun

Pronunciation: /ˈnjuːkliˌɔɪd/

Definitions

1. A region within a prokaryotic cell containing the organism's genetic material, typically appearing as a distinct area without a surrounding membrane
2. A non-membrane-bound area within a prokaryotic cell that houses the genetic information of the organism and is distinct from other cellular components
3. The genetic material of a prokaryote is organized in a region known for lacking a surrounding membrane, which sets it apart within the cell

Etymology: The word "nucleoid" is a modern scientific coinage built from two classical pieces. "Nucleo-" comes from Latin "nucleus," meaning a kernel or the inner part of a nut, and "-oid" comes from Greek "-oeidēs," meaning "having the form of" or "like." Put together, a nucleoid is literally "like a nucleus." The name fits the structure it describes. Eukaryotic cells, such as those in plants and animals, keep their DNA inside a membrane-bound nucleus. Prokaryotes such as bacteria have no such membrane, yet their genetic material is still gathered into a compact region. Scientists needed a term for that region that signalled its resemblance to a nucleus without implying it was one, and "nucleoid" was built to do exactly that.

Synonyms: nucleus, core, center, heart, hub