What do ribosomal RNA do?

• A. Facilitate pairing of tRNA anticodons with mRNA codons
• B. Copy DNA into RNA
• C. Transport amino acids in the cytosol
• D. Catalyze DNA replication

Answer: (A)

Ribosomal RNA is part of the ribosome, the machine that translates mRNA into protein. During translation, the ribosome must pair each mRNA codon with the correct tRNA anticodon. The rRNA in the decoding center helps align and stabilize that codon–anticodon pairing, ensuring the right tRNA enters the ribosome and that the amino acid it carries is added in the correct order. It also contributes to the catalytic activity of forming peptide bonds, tying the amino acids together as translation proceeds. In short, rRNA’s role is to ensure accurate pairing and proper functioning of the translation machinery, which is why this option best describes its job. Copying DNA into RNA is done by RNA polymerase, transporting amino acids is the job of tRNA, and catalyzing DNA replication is done by DNA polymerases.