Ribosomes are composed of two subunits made of what components?

• A. A large subunit only
• B. A small subunit only
• C. A large and a small subunit made of proteins and ribosomal RNA
• D. DNA and proteins

Answer: (C)

Ribosomes are ribonucleoprotein machines made of two subunits, a large and a small one. Each subunit contains ribosomal RNA and proteins. The rRNA provides the central scaffold and the catalytic activity (peptide bond formation in the large subunit), while the proteins stabilize the structure and assist in assembling and interacting with mRNA and tRNAs. DNA isn’t a component of the ribosome; it’s the template for the ribosomal RNA genes. This is why the description of the two subunits being made of proteins and ribosomal RNA is the best answer.