Practice question

First division segregation describes separation allelic differences at anaphase I without any crossover between gene and centromere region. Homologous centromeres carrying different alleles segregate reductionally to opposite poles, sister chromatids stay together until meiosis II, yielding ordered asci with blocks four identical spores grouped, such as AAAAaaaa pattern. Pattern indicates locus remained linked to centromere throughout meiosis I because chromatids did not exchange. No exchange between gene and centromere preserves parental centromere-allele associations, defining FDS signature valuable for centromere proximity mapping.