Final answer:
During prophase I of meiosis, homologous chromosomes with a pericentric inversion form a loop structure for accurate gene alignment and recombination.
Step-by-step explanation:
When one homologous chromosome undergoes an inversion but the other does not, the individual is described as an inversion heterozygote. To maintain point-for-point synapsis during meiosis, one homolog must form a loop, and the other homolog must mold around it. This topology ensures that the genes are correctly aligned but can result in regions of imprecise synapsis. Therefore, the structure that these homologs would assume in order to pair accurately along their lengths is the formation of a loop.
When a pericentric inversion occurs in one of two homologs prior to meiosis, the homologs form a specific structure to pair accurately along their lengths. This occurs during prophase I, where the chromosome with the inversion forms a loop to maintain point-for-point interaction during synapsis. This inversion pairing is necessary to ensure gene alignment and to facilitate recombination. This process can sometimes involve regions of imprecise synapsis due to the distortion required to align the inverted and non-inverted chromosomes.