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Explain the structure found in nucleus which is responsible for rRNA synthesis.

GeneralClass 12AllAnswered 27 Mar 2026
Answer

Nucleolus (plural: nucleoli)

Structure:

  • Spherical, electron-dense body
  • Located in nucleoplasm
  • Not membrane-bound
  • Larger and more numerous in cells with high protein synthesis activity

Composition:

  • Ribosomal DNA (rDNA) – genes encoding rRNA
  • Proteins (ribosomal proteins, transcription factors)
  • Nascent rRNA molecules

Function:

  • Site of ribosomal RNA (rRNA) synthesis (transcription of rDNA)
  • Ribosome biogenesis – assembly of ribosomal subunits
  • Processing and modification of rRNA

Clinical significance: Nucleolus size correlates with cell metabolic activity; nucleolar changes are markers in cancer diagnosis.

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