P rogress through m eiosis 14.1 M ole cular interactions M Each chrom osome has chrom somes Introduction AN replicated, and consists of become visible, often 2 sister chromatid s attached to nuclear envelope A MVV Figure 14.1 Recombination Zygotene A Initiation Chromosom es begin occurs during the first meiotic reglon or regions AAAAA prophase. The stages of N prophase are defined by the P achytene appearance of the Synaptonem al complex extends chromosomes each of which along entire length of bosom es consists of two replicas(sister ) /VA Strand exchange NUM VA Single strands exchange chromatids), although the Diplotene duplicated state becomes Chromosomes A人A in of exchange separate but are held visible only at the end. The together by hastata N molecular interactions of any individual crossing-over event Diakinesis involve two of the four duplex Chromosom es A Resolution condense, detach from envelope DNAS chiasmata remain. a 八 4 chromatids becom 请莘大Figure 14.1 Recombination occurs during the first meiotic prophase. The stages of prophase are defined by the appearance of the chromosomes, each of which consists of two replicas (sister chromatids), although the duplicated state becomes visible only at the end. The molecular interactions of any individual crossing-over event involve two of the four duplex DNAs. 14.1 Introduction