homologous recombination.

Question

The process of homologous recombination, to repair a double strand DNA break, begins with the nucleolytic processing of the 5’ ends.

why this step is necessary for homologous recombination to occur, and why nuclease digestion of the 3’ ends would NOT support homologous recombination

Answer 1

Hi Ibrahim,

Essentially, the 5' ends of the broken DNA are degraded to create a 3' single-stranded DNA overhang, which can then act as a primer for DNA polymerase to recognize and extend it, synthesizing new DNA for repair.

In contrast, if the 3' end were to be digested it would create a 5' single stranded overhang which DNA polymerase can not extend (it functions by adding nucleotides to the hydroxyl group located on the 3' overhang as discussed above.)