What does synapsis refer to in the process of meiosis?

Synapsis is a vital process that occurs during the prophase I stage of meiosis, where homologous chromosomes pair up closely along their lengths. This pairing is essential for genetic recombination, as it allows for crossing over, where segments of DNA are exchanged between the homologous chromosomes. This genetic exchange increases genetic diversity in gametes, which is fundamental for evolution and the adaptation of populations over time.

The term "synapsis" specifically describes the moment when these homologous chromosomes align and physically connect through structures called synaptonemal complexes, facilitating the precise exchange of genetic material. This process is crucial for ensuring that each gamete receives the correct number of chromosomes and promotes genetic variation in sexually reproducing organisms.