Sister chromatids are identical copies of a chromosome. Compare sister chromatids to homologous chromosomes, which are the two different copies of the same chromosome that diploid organisms (like humans) inherit, one from each parent. In other words, sister chromatids contain the same genes and same alleles, and homologous chromosomes contain the same genes but two copies of alleles, each of which might or might not be the same as each other. Two chromosomes are said to be homologous when they have the same alleles at the same positions (loci) for all the genes they contain, besides being of the same length. ... Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... An allele is any one of a number of alternative forms of the same gene occupying a given locus (position) on a chromosome. ...
A full set of sister chromatids is created during the S subphase of interphase, when all the DNA in a cell is replicated. Identical chromosome pairs are separated into two different cells during mitosis, or cellular division. To meet Wikipedias quality standards, this article or section may require cleanup. ... A cell in early anaphase Mitosis is the process by which a cell separates its duplicated genome into two identical halves. ...
Sisterchromatid segregation is dependent on sisterchromatid cohesion, which is only established during replication and holds sisters together until anaphase.
Sisterchromatid cohesion plays a pivotal role during both divisions, by ensuring that chromosomes containing homolog centromeres segregate to opposite poles during meiosis I, and chromosomes containing sistercentromeres segregate during meiosis II.
First, sister kinetochore attachment to opposite poles is prevented during meiosis I. Second, sisterchromatid cohesion distal to cross-overs holds homologs together, promoting attachment of homologs to opposite poles.
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