* Ribosomal RNA (rRNA): This is a type of RNA that provides the structural framework for the ribosome and also participates in the catalytic steps of protein synthesis.

* Ribosomal proteins: These proteins bind to the rRNA, helping to shape the ribosome and stabilize its structure. They also play a role in regulating the ribosome's function.

In summary, ribosomes are complex molecular machines composed of rRNA and ribosomal proteins that work together to translate genetic information from mRNA into proteins.