There are five major types of RNA found in eukaryotic cells: 1) heterogeneous nuclear RNA (hnRNA), 2) messenger RNA (mRNA), 3) transfer RNA (tRNA), 4) ribosomal RNA (rRNA), and 5) small nuclear RNA. The primary types of RNA are mRNA, tRNA, and rRNA. Messenger RNA, a single strand copied from a DNA strand, carries the genetic code from the DNA to the site of protein synthesis on the ribosomes. The most abundant type of RNA, rRNA, participates in protein synthesis in the ribosomes. Transfer (tRNA) is the translation molecule. Each tRNA molecule carries a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA.