The structure inside the nucleus where RNA is transcribed is called the nucleolus.

Here's a breakdown:

* Nucleus: The control center of the cell, containing the genetic material (DNA).

* Nucleolus: A dense region within the nucleus where ribosomal RNA (rRNA) is synthesized and assembled with proteins to form ribosomes.

* Transcription: The process of copying DNA into RNA.

How it works:

1. DNA template: The DNA within the nucleus contains the genetic code for making proteins.

2. Transcription: The enzyme RNA polymerase binds to the DNA and uses it as a template to create a complementary RNA molecule.

3. rRNA synthesis: In the nucleolus, rRNA is transcribed from specific DNA regions.

4. Ribosome assembly: The rRNA combines with proteins to form ribosomes, the protein-making machinery of the cell.

So, while the entire nucleus is involved in transcription, the nucleolus is the specialized region dedicated to rRNA synthesis and ribosome assembly, crucial steps in the overall process of protein production.