Trying to work out and reason through this practice question tohelp me on my test.
"Briefly explain why non-homologous end joining is overwhelmingfavored over homologous recombination repair for fixing doublestrand DNA breaks in mammalian cells in G1. Why is this biasreversed during G2?"
So I reckon that non-homologous end joining is favored in G1because although original base pairing is lost and chewed back byexonuclease before the DNA is re-ligated, the loss of base pairsisn't critical due to the imminent S phase, which will ensure theDNA is further re-synthesized, thus mitigating the effect of lostbase pairs.
However, for G2, nonhomologous recomb. is favored because in thismethod base pairs are re-added before getting re-ligated, ensuringno bases are lost. This is critical because the next phase ismitosis, and all of the DNA must be synthesized to this point; anyloss of DNA before mitosis would probably lead to mutations whenthe cell eventually divides.
Is my reasoning accurate? Please chime in anddiscuss!
Trying to work out and reason through this practice question tohelp me on my test.
"Briefly explain why non-homologous end joining is overwhelmingfavored over homologous recombination repair for fixing doublestrand DNA breaks in mammalian cells in G1. Why is this biasreversed during G2?"
So I reckon that non-homologous end joining is favored in G1because although original base pairing is lost and chewed back byexonuclease before the DNA is re-ligated, the loss of base pairsisn't critical due to the imminent S phase, which will ensure theDNA is further re-synthesized, thus mitigating the effect of lostbase pairs.
However, for G2, nonhomologous recomb. is favored because in thismethod base pairs are re-added before getting re-ligated, ensuringno bases are lost. This is critical because the next phase ismitosis, and all of the DNA must be synthesized to this point; anyloss of DNA before mitosis would probably lead to mutations whenthe cell eventually divides.
Is my reasoning accurate? Please chime in anddiscuss!
