Cell Component
macronucleus
mac·ro·nu·cle·us [ mak-roh-noo-klee-uh s, -nyoo- ]
Subclass of:
Cell Nucleus
Definitions related to macronucleus:
  • A membrane-bounded organelle of ciliated protozoan cells that contains polyploid copies of a portion of the cell's complete genome. Transcription of genes occurs in macronuclei. Some ciliate species may contain multiple macronuclei per cell.
    Gene Ontology Dictionary
    Gene Ontology Consortium, 2021
  • The larger of two types of nuclei in ciliate protozoans. It is the transcriptionally active nucleus of the vegetative cells as distinguished from the smaller transcriptionally inert GERMLINE MICRONUCLEUS.
    NLM Medical Subject Headings
    U.S. National Library of Medicine, 2025
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