tRNA(n) + a ribonucleoside 5'-diphosphate => tRNA(n+1) + phosphate
trna(n) + a ribonucleoside 5'-diphosphate => trna(n+1) + phosphate
tRNA(n) + a ribonucleoside 5'-diphosphate => tRNA(n+1) + phosphate
trna(n) + a ribonucleoside 5'-diphosphate => trna(n+1) + phosphate