crossing-over The exchange of genetic material between homologous chromosomes by breakage and reunion. This occurs during pairing of chromosomes at prophase I of meiosis, and in some organisms (for example certain fungi, and insects such as Drosophila) may also occur at mitosis. The temporary joins between chromosomes during crossing-over are called chiasmata.

crossing-over The exchange of genetic material between homologous chromosomes by breakage and reunion. This occurs during pairing of chromosomes at meiosis, and in some organisms (e.g. certain fungi, and insects such as Drosophila) may also occur at mitosis. The temporary joins between chromosomes during crossing-over are called chiasmata.