Why must happen prior meiosis i?

Prior to meiOSis I, DNA replication must occur during the S phase of the cell cycle. This replication ensures that each chromosome consists of two sister chromatids, which are necessary for the subsequent steps of meiOSis. Additionally, homologous chromosomes pair and undergo genetic recombination during prophase I, setting the stage for the reduction of chromosome number and genetic diversity in the resulting gametes.