As a result of crossing over, sister chromatids are no

Last updated: 7/8/2022

As a result of crossing over, sister chromatids are no longer identical to each other. Crossing over prevents homologous chromosomes from separating during meiosis I. For crossing over to occur, homologous chromosomes must align precisely early in prophase I so that nonsister chromatids can exchange corresponding segments of DNA. Crossing over occurs at the ends of chromosomes, rather than near the centromeres.