Which RNA molecule forms the core of the ribosome?

• A. Ribosomal RNA
• B. Small nuclear RNA
• C. Messenger RNA
• D. Transfer RNA

Answer: (A)

Ribosomal RNA forms the core of the ribosome, providing both the structural scaffold that organizes ribosomal proteins and the catalytic component that drives protein synthesis. The peptidyl transferase activity—forming peptide bonds between amino acids—resides in the rRNA of the large subunit, making the ribosome a ribozyme rather than a protein-only enzyme. Other RNA types have distinct roles: small nuclear RNA participates in splicing of pre-mRNA, messenger RNA carries the genetic code for protein sequences, and transfer RNA brings in specific amino acids during translation. Thus, the RNA responsible for the ribosome’s essential function and architecture is ribosomal RNA.