The purpose of chromosomes during meiosis is to ensure the proper segregation of genetic material into gametes. During meiosis, chromosomes undergo replication, followed by two rounds of division that reduce the chromosome number by half, creating haploid cells. This reduction is crucial for sexual reproduction because it allows for the combination of genetic material from two parents during fertilization. Correct chromosome segregation is vital to prevent disorders caused by aneuploidy, which can lead to conditions like Down syndrome.