Final answer:
Ribosomal RNA (rRNA) is the most abundant RNA in cells due to its structural role in the many ribosomes required for protein synthesis.
Step-by-step explanation:
The Most Abundant Class of RNA in Cells
In terms of abundance, ribosomal RNA (rRNA) is the most prevalent type of RNA found in cells. rRNA is a structural component of ribosomes, which are the cellular organelles where protein synthesis occurs. Ribosomes consist of two subunits, each made up of rRNA and about 50 ribosomal proteins. Given the high number of ribosomes present in cells to meet the protein synthesis demands, rRNA vastly outnumbers the other types of RNA, including messenger RNA (mRNA), transfer RNA (tRNA), and microRNA (miRNA).
While the function of mRNA is to carry genetic information from DNA to the cytoplasm for protein production, and tRNA brings specific amino acids to the ribosomes during protein synthesis, it is the rRNA that makes up the bulk of the ribosomal structure and thus constitutes most of the RNA in a cell.