What is rRNA?

• A. The type of RNA that, together with proteins, makes up ribosomes; the most abundant type of RNA.
• B. The RNA that carries amino acids to the ribosome.
• C. The RNA that codes for proteins.
• D. A DNA sequence used for transcription.

Answer: (A)

rRNA stands for ribosomal RNA. It’s the RNA component of ribosomes, the molecular machines that synthesize proteins. Along with ribosomal proteins, rRNA forms the two ribosomal subunits and provides the core structure and catalytic center that stitches amino acids together to make a protein. Because cells need lots of protein, rRNA is the most abundant type of RNA. The other options don’t fit: tRNA brings amino acids to the ribosome, mRNA carries the genetic code from DNA to the ribosome, and a DNA sequence used for transcription is a gene or regulatory region, not RNA itself.