plz giv me a proper explanation of prophase 1 with diagrams

Prophase I − longest phase and is further sub-divided into 5 phases

  • Leptotene − Condensation makes chromosomes become distinct and compact.

  • Zygotene − Homologous chromosomes start pairing together by a process called synapsis to form a complex structure called synaptonemal complex. Two synapsed homologous chromosomes form a complex called bivalent or tetrad.

  • Pachytene − Longest phase of prophase I
    Recombination nodules appear in this stage at the sites where crossing over has to take place between non-sister chromatids of homologous chromosomes.

  • Diplotene − Synaptonemal complex dissolves and recombinants separate from each other except at crossover sites to form X-shaped structure called chiasmata.

  • Diakinesis − Chiasmata terminalises and chromosomes condense. Meiotic spindle assembles and nucleolus and nuclear envelope disappear.

  • 5
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