Question

q) While there are many types of DNA repair mechanisms, many of them really only work during the process of DNA replication. If we’re looking at a cell that has terminally divided (meaning it’s not going to go through the cell cycle anymore), what types of repair mechanisms are still available to that cell?

Answer 1

DNA is not only repaired during replication but also when the cell is under environmental stress there may be the possibility of DNA damage. The environmental stress includes all the types of radiations like UV, X-ray, cosmic rays, gamma rays, etc are responsible for the DNA damage. Apart from the environmental stress the endogenous stress of the cell also causes DNA damage, for example, the formation of reactive oxygen species which damage the DNA. Therefore, there is various mechanism are available to repair the DNA damage. The mechanisms include :

(i) Nucleotide excision repair

In this repair mechanism, the structurally altered nucleotide is removed by DNA repair machinery. For example, In E.coli the protein complex Uvr ABC helps in the repair of DNA damage by UV rays.

(ii) Base Excision Repair

In base excision repair, the mutated base is removed and a normal base is added.