Which type of RNA combines with proteins to form ribosomes?

Ribosomal RNA (rRNA) plays a crucial role in the formation of ribosomes, which are the cellular structures responsible for protein synthesis. rRNA, along with various proteins, makes up the ribosome's structure and is integral to its function. It facilitates the binding of messenger RNA (mRNA) and transfer RNA (tRNA) during protein synthesis, ensuring accurate translation of genetic information into proteins.

Messenger RNA carries the genetic blueprint from DNA to the ribosomes but does not contribute to the structural formation of ribosomes themselves. Transfer RNA acts as an adaptor, bringing amino acids to the ribosome during the translation process, but like mRNA, it does not form a part of the ribosomal structure. Nuclear RNA is involved in the processing and regulation of other types of RNA within the nucleus and is not directly involved in ribosome formation. Thus, ribosomal RNA is specifically responsible for building the ribosomal scaffold needed for protein synthesis.