It can also be formed by exchange involving one arm of a chromosome and its homolog (or sister chromatid) at the proximal edge of the arm, adjacent to the centromere.
Sister chromatid cohesion is essential for the correct distribution of genetic information between daughter cells and the repair of damaged chromosomes.
Chemically modified bases can be bypassed by either error-prone or error-free translesion polymerases, or through genetic exchange with the sister chromatid.
Four to five sister chromatid exchange per chromosome pair, per mitosis is in the normal distribution, 14-100 exchanges is not normal and presents a danger to the organism.
Establishment of sister chromatid cohesion is the process by which chromatin-associated cohesin protein becomes competent to physically bind together the sister chromatids.