rRNA. rRNA, or ribosomal RNA, is a major component of ribosomes. After transcription, these RNA molecules travel to the cytoplasm and join with other rRNAs and many proteins to form a ribosome. rRNA is used both for structural and functional purposes.NA, or ribonucleic acid, is a linear polymer of adenine, thymine, cytosine, and uracil that is created in the cell by a process called transcription, and it differs from DNA in several ways. First, the ribose sugars on DNA nucleotides are short one hydroxyl group compared to RNA, hence the name deoxyribonucleic acid.