Final answer:
rRNA is a major constituent of ribosomes and provides structural support as well as catalytic functions in the ribosomes during protein synthesis.
Step-by-step explanation:
Ribosomes are composed of rRNA and protein.
As its name suggests, rRNA is a major constituent of ribosomes, composing up to about 60% of the ribosome by mass and providing the location where the mRNA binds.
The rRNA ensures the proper alignment of the mRNA, tRNA, and the ribosomes; the rRNA of the ribosome also has an enzymatic activity (peptidyl transferase) and catalyzes the formation of the peptide bonds between two aligned amino acids during protein synthesis.
Although rRNA had long been thought to serve primarily a structural role, its catalytic role within the ribosome was proven in 2000.-
Scientists in the laboratories of Thomas Steitz (1940-) and Peter Moore (1939-) at Yale University were able to crystallize the ribosome structure from Haloarcula marismortui, a halophilic archaeon isolated from the Dead Sea.