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  2. Prophase - Wikipedia

    en.wikipedia.org/wiki/Prophase

    Prophase is the first step of cell division in mitosis. As it occurs after G2 of interphase, DNA has been already replicated when prophase begins. [1] Fluorescence microscope image of two mouse cell nuclei in prophase (scale bar is 5 μm).

  3. Chromosomal crossover - Wikipedia

    en.wikipedia.org/wiki/Chromosomal_crossover

    Crossing over occurs between prophase I and metaphase I and is the process where two homologous non-sister chromatids pair up with each other and exchange different segments of genetic material to form two recombinant chromosome sister chromatids. It can also happen during mitotic division, [1] which may

  4. Zygotene - Wikipedia

    en.wikipedia.org/wiki/Zygotene

    Zygotene (from greek "paired threads" [1]) is the second stage of prophase I during meiosis, the specialized cell division that reduces the chromosome number by half to produce haploid gametes. It follows the Leptotene stage and is followed by Pachytene stage.

  5. Leptotene stage - Wikipedia

    en.wikipedia.org/wiki/Leptotene_stage

    The leptotene stage, also known as leptonema, is the first of five substages of prophase I during meiosis, ... [1]: 27 [2]: 353 Each chromosome consists of two ...

  6. Genetic recombination - Wikipedia

    en.wikipedia.org/wiki/Genetic_recombination

    Two of the four chromatids present early in meiosis (prophase I) are paired with each other and able to interact. Recombination, in this model, is initiated by a double-strand break (or gap) shown in the DNA molecule (chromatid) at the top of the figure. Other types of DNA damage may also initiate recombination.

  7. Homologous chromosome - Wikipedia

    en.wikipedia.org/wiki/Homologous_chromosome

    In prophase I of meiosis I, each chromosome is aligned with its homologous partner and pairs completely. In prophase I, the DNA has already undergone replication so each chromosome consists of two identical chromatids connected by a common centromere. [10] During the zygotene stage of prophase I, the homologous chromosomes pair up with each ...

  8. Bivalent (genetics) - Wikipedia

    en.wikipedia.org/wiki/Bivalent_(genetics)

    The formation of a bivalent occurs during the first division of meiosis (in the zygotene stage of meiotic prophase 1). In most organisms, each replicated chromosome (composed of two identical sister chromatids [1] [2]) elicits formation of DNA double-strand breaks during the leptotene phase. [3]

  9. Synaptonemal complex - Wikipedia

    en.wikipedia.org/wiki/Synaptonemal_complex

    The synaptonemal complex is a tripartite structure consisting of two parallel lateral regions and a central element. This "tripartite structure" is seen during the pachytene stage of the first meiotic prophase, both in males and in females during gametogenesis.