Human Peripheral blood exposed with tritiated water at variousdoses for 54 hr was examined to observe the chromosome and chromatid abe-rrations at metaphases in the first mitosis of lymphocytes.
So now End 1 is placed near a similar nucleotide sequence, called the homologous sequence, because it's found in the same spot on the homologous sister chromatid.
Since homology-directed repair uses a sister chromatid as a template, this is a more reliable repair mechanism than non-homologous end joining because there's no loss of nucleotides.