Where is ribosomal RNA transcribed?

Ribosomal RNA (rRNA) is transcribed in the nucleolus, which is a distinct region within the nucleus of eukaryotic cells. The nucleolus is specifically involved in synthesizing rRNA and assembling ribosomal subunits. This process is crucial for protein synthesis, as ribosomes are essential for translating messenger RNA into proteins. While the nucleus contains the genetic material and is the overall site of transcription, the specialized structure of the nucleolus is dedicated to the production of rRNA, distinguishing it from other cellular processes that occur in the nucleus or cytoplasm. The endoplasmic reticulum and cytoplasm, although important for protein synthesis and other functions, are not involved in the transcription of rRNA.