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Sister chromatid exchange (SCE) is the exchange of genetic material between two identical sister chromatids. It was first discovered by using the Giemsa staining method on one chromatid belonging to the sister chromatid complex before anaphase in mitosis. The staining revealed that few segments were passed to the sister chromatid which were not ...
Afterwards, the 3’ ssDNA invades the template DNA, and displaces a DNA strand to form a D-loop. DNA polymerase and other accessory factors follows by replacing the missing DNA via DNA synthesis. Ligase then attaches the DNA strand break, [ 10 ] resulting in the formation of 2 Holliday junctions .
Gene conversion is the process by which one DNA sequence replaces a homologous sequence such that the sequences become identical after the conversion. [1] Gene conversion can be either allelic, meaning that one allele of the same gene replaces another allele, or ectopic, meaning that one paralogous DNA sequence converts another.
However, in the G2 stage of the cell cycle (following DNA replication), a second homologous DNA molecule is also present: the sister chromatid. Evidence indicates that, due to the special nearby relationship they share, sister chromatids are not only preferred over distant homologous chromatids as substrates for recombinational repair, but have ...
In cells that divide through mitosis, the recipient DNA duplex is generally a sister chromatid, which is identical to the damaged DNA molecule and provides a template for repair. In meiosis, however, the recipient DNA tends to be from a similar but not necessarily identical homologous chromosome. [43]
Once DNA replication has finished, in eukaryotes the DNA molecule is compacted and condensed, to form the mitotic chromosomes, each one constituted by two sister chromatids, which stay held together by the establishment of cohesion between them; each chromatid is a complete DNA molecule, attached via microtubules to one of the two centrosomes ...
Sister chromatid crossover events are known to occur at a rate of several crossover events per cell per division in eukaryotes. [31] Most of these events involve an exchange of equal amounts of genetic information, but unequal exchanges may occur due to sequence mismatch.
A sister chromatid refers to the identical copies formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be 'one-half' of the duplicated chromosome. A pair of sister chromatids is called a dyad.