noun, plural: gap genes
Any of the segmentation genes whose expression results in the formation of gaps in the normal pattern of structure in the embryo, as well as the activation of pair-rule genes.
The gap genes are the first set of zygotic genes activated after fertilization. Its expression results in the formation of broad bands in the embryo. Example of gap gene is Kruppel gene.
See also: segmentation gene, zygotic gene.