Here's why:
* Ribosomes are the protein synthesis machinery. They read the genetic code from messenger RNA (mRNA) and use it to assemble amino acids into polypeptide chains, which fold into functional proteins.
* Ribosomes are found in all living cells. They can be free-floating in the cytoplasm or attached to the endoplasmic reticulum (ER).
* Free ribosomes produce proteins that will remain in the cytoplasm.
* Ribosomes attached to the ER produce proteins that are destined for export out of the cell, or for insertion into membranes.
While other organelles play a role in protein production and processing (like the endoplasmic reticulum and Golgi apparatus), ribosomes are the primary site of protein synthesis.
