29.2 Fly development uses a cascade of transcription factors Homeotic genes are defined by mutations that convert one body part into another, for example, an insect leg may replace an antenna Segmentation genes are concerned with controlling the number or polarity of body segments in insects 消当Homeotic genes are defined by mutations that convert one body part into another; for example, an insect leg may replace an antenna. Segmentation genes are concerned with controlling the number or polarity of body segments in insects. 29.2 Fly development uses a cascade of transcription factors