can dna be fixed once it is damaged
The resulting 29 nucleotide segment of damaged DNA is then unwound, the gap is filled (DNA polymerase) and the nick sealed (ligase). Direct Repair of Damaged DNA. Sometimes damage to a base can be directly repaired by specialized enzymes without having to excise the nucleotide. Recombination Repair. This mechanism enables a cell to replicate past the damage and fix it later.