What are polyribosomes?

• A. A chain of ribosomes producing the same protein
• B. A single ribosome
• C. Ribosome attached to the ER only
• D. A misfolded ribosome

Answer: (A)

Polyribosomes, or polysomes, are groups of ribosomes bound to a single mRNA molecule, with each ribosome translating the same message at the same time. This setup lets many ribosomes work in parallel, producing multiple copies of the same protein from one mRNA template and greatly speeding up protein synthesis. If you only had a single ribosome, you’d get one protein chain at a time, which is much less efficient. The fact that ribosomes can be free in the cytoplasm or attached to the endoplasmic reticulum shows localization flexibility, but that isn’t what defines polyribosomes—the defining feature is the multiple ribosomes translating one mRNA. The idea of a misfolded ribosome isn’t a recognized concept here, since ribosomes aren’t described by folding status in this context.