Final answer:
During prophase I of meiosis I, homologous chromosomes come together and align side by side, a process supported by the synaptonemal complex and called synapsis. This leads to crossing-over, contributing to genetic diversity in the resulting gametes.
Step-by-step explanation:
During meiosis I, specifically in prophase I, homologous chromosomes undergo a process called synapsis. This involves the chromosomes coming together and lining up side by side in perfect alignment. A lattice of proteins known as the synaptonemal complex assists in this tight pairing, allowing for the alignment of genes on the chromatids of the homologous chromosomes. The formation of the synapse is essential for the process of crossing-over, where genetic materials are exchanged between the homologous chromosomes, creating genetic diversity.
Following synapsis and crossing-over, the intricate process continues with the breakdown of the synaptonemal complex, and the chromosomes then move to metaphase I, where they line up in pairs at the center of the cell before eventually being separated and pulled to opposite poles in anaphase I.