Messenger RNA (mRNA) is attached to the ribosome during protein construction. The ribosome is a complex structure composed of RNA and protein components that synthesises proteins by translating the genetic information encoded in mRNA. The mRNA molecule binds to the ribosome at a specific site called the ribosome binding site (RBS) or the Shine-Dalgarno sequence in bacteria. This attachment of mRNA to the ribosome is essential for the process of protein synthesis, which occurs in the cytoplasm of cells.