RNA molecules present in the cell (in at least 20 varieties, each variety capable of combining with a specific amino acid) that attach the correct amino acid to the protein chain that is being synthesized at the ribosome of the cell (according to directions coded in the mRNA)
"The lab results showed a mutation in the tRNA genes that prevented certain varieties from attaching their specific amino acids during protein synthesis."
Initialism of transfer RNA.
"The textbook lists both "tRNA" and "trna" as acceptable spellings for transfer RNA, so I used whichever felt more comfortable in my notes."
Alternative form of tRNA