What does rRNA do?

What does rRNA do?

• A. Forms ribosomes
• B. Carries amino acids
• C. Catalyzes transcription
• D. Regulates gene expression

Answer: (A)

rRNA forms ribosomes, the molecular machines that translate mRNA into proteins. Ribosomes are made of ribosomal RNA and proteins, with rRNA providing the core structure of both subunits and the site where peptide bonds form. In the large subunit, the rRNA acts as a ribozyme to catalyze the formation of peptide bonds between adjacent amino acids as they’re brought in by tRNAs, building the polypeptide chain dictated by the mRNA sequence. This is the heart of translation. Carrying amino acids is the job of tRNA, not rRNA. Transcription is carried out by RNA polymerase, not rRNA. Regulation of gene expression involves various proteins and regulatory RNAs, not the ribosomal RNA itself. So the role of rRNA is best described by its foundational part in forming the ribosome and enabling protein synthesis.

rRNA forms ribosomes, the molecular machines that translate mRNA into proteins. Ribosomes are made of ribosomal RNA and proteins, with rRNA providing the core structure of both subunits and the site where peptide bonds form. In the large subunit, the rRNA acts as a ribozyme to catalyze the formation of peptide bonds between adjacent amino acids as they’re brought in by tRNAs, building the polypeptide chain dictated by the mRNA sequence. This is the heart of translation.

Carrying amino acids is the job of tRNA, not rRNA. Transcription is carried out by RNA polymerase, not rRNA. Regulation of gene expression involves various proteins and regulatory RNAs, not the ribosomal RNA itself. So the role of rRNA is best described by its foundational part in forming the ribosome and enabling protein synthesis.