Ribosomal RNA (rRNA)

Summary

Ribosomal RNA, or rRNA, is a type of non-coding RNA which functions as the main building block of ribosomes. rRNA is synthesized mainly by RNA polymerase I in the nucleolus of eukaryotes, and by RNA polymerase in the cytoplasm of prokaryotes.

Key Points

• Ribosomal RNA (rRNA)
  • Characteristics
    • Class of non-coding RNA 
      • Does not code for proteins
      • Also known as functional RNA
    • Found in both prokaryotes and eukaryotes
  • Function
    • Forms ribosomes
      • Combines with proteins to form molecular machinery used to assemble proteins from mRNA in the cytoplasm 
  • Synthesis
    • Eukaryotes
      • Transcribed mostly by RNA Polymerase I
        • Occurs in the nucleolus
        • Partially by RNA Polymerase III in the nucleus
    • Prokaryotes
      • Transcribed by RNA Polymerase in the cytoplasm