The major role of tRNA is to translate mRNA sequence into amino acid sequence. A tRNA molecule consists of 70-80 nucleotides. In dihydrouridine, a hydrogen atom is added to each C5 and C6 of uracil. In pseudouridine, the ribose is attached to C5, instead of the normal N1.
Inosine plays an important role in codon recognition.
In addition to these modifications, a few nucleosides are methylated.