a tRNA with a 3' CCA end + 2 CTP + ATP => a tRNA with a 3' CCACCA end + 3 diphosphate
a trna with a 3' cca end + 2 ctp + atp => a trna with a 3' ccacca end + 3 diphosphate
a tRNA with a 3' CCA end + 2 CTP + ATP => a tRNA with a 3' CCACCA end + 3 diphosphate
a trna with a 3' cca end + 2 ctp + atp => a trna with a 3' ccacca end + 3 diphosphate