Nick translation. The polymerase and 5' exonuclease activities of DNA polymerase I are coordinated in replacing the RNA primer with DNA by the process of nick translation. (a) Movement of the nick by one position to the left, as a UMP residue of RNA is replaced by a dTMP residue of DNA. (b) The basis for the term nick translation: the nick moves to the left by n nucleotides, with no change in the total number of nucleotides polymerized. rNMP = ribonucleoside triphosphate.