American Society for Clinical Pathology (ASCP) Histotechnologist Practice Test

Which of the following is not a role of ribosomes?

1. Protein synthesis

2. Packaging proteins

3. Translating mRNA

4. Building polypeptides

The correct answer is: Packaging proteins

Ribosomes play a crucial role in the process of protein synthesis, which encompasses translating messenger RNA (mRNA) into polypeptide chains, ultimately leading to the production of proteins. They are the cellular machinery responsible for reading the genetic code carried by mRNA and facilitating the assembly of amino acids into a polypeptide chain, which is built through peptide bonds. While ribosomes are involved in both translating mRNA and building polypeptides directly through their function as sites of translation, they do not actively engage in the packaging of proteins. The packaging of proteins typically occurs in the endoplasmic reticulum and Golgi apparatus, where synthesized proteins are modified, sorted, and prepared for transport to their final destinations within the cell or outside of it. Thus, the statement that packaging proteins is a role of ribosomes is incorrect, as this function is attributed to different cellular structures involved in post-translational modification and transport, rather than the ribosome itself.