A
sister chromatid refers to either of the two identical copies (
chromatids) formed by the replication of a single
chromosome, with both copies joined together by a common
centromere. In other words, a sister chromatid may also be said as 'one-half' of the duplicated chromosome. A full set of sister chromatids is created during the synthesis (S) phase of
interphase, when all the chromosomes in a cell are replicated. The two sister chromatids are separated from each other into two different cells during
mitosis and during the second division of
meiosis straight after
fertilization during
sexual reproduction.