Practice question

Homeotic selector genes clustered in HOM-C complex on right arm chromosome 3 covering Antennapedia complex at 84A-84B and Bithorax at 89E, separated by ten megabases but linked via shared Polycomb response elements. This location contrasts with segmentation genes on X and second chromosomes. Clustering permits colinear expression where 3' genes express anteriorly and 5' posteriorly, maintained by chromatin domains and insulators like Fab-7 and Mcp. Disruption via translocations misregulates Hox expression causing homeotic transformations confirming importance of chromosomal organization for precise developmental timing and positional identity establishment during embryogenesis.