Practice question

Neurospora ascus shape results elongation ascogenous hyphae producing narrow cylindrical perithecial asci where width approximates spore diameter only slightly larger, constraining spores linearly. Nuclear divisions align along length axis, so meiosis I spindle, meiosis II spindles, and postmeiotic mitosis maintain linear order, generating file eight spores where sister products from mitosis sit adjacent. Microscopic squashes reveal order readily scored as 4:4 or 2:2:2:2 patterns. Linear morphology contrasts with spherical yeast asci randomizing positions. Linear arrangement crucial for distinguishing segregation patterns underlying gene-centromere mapping and interference analysis.