BIOL303 Chapter Notes - Chapter 7: Gap Gene, Morphogen, Blastoderm
18 Nov 2015
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Maternal effect genes, produces mrna"s localized to different regions of the egg, will diffuse. These genes express in broad over lapping domains, will encode transcription factors, differing combinations and concentrations of gap gene proteins that regulate transcription pair-rule genes (striped pattern perpendicular to ap axis)! Pair-rule genes encode tf"s that activate the segment polarity genes, whose mrna and protein products divide the embryo into 14-segment wide units, establishing the periodicity of the embryo! selector genes, determines the developmental fate of each segment! The protein products of gap, pair-rule and segment genes all interact to regulate homeotic. Mutations, one structure will replace another in an area (example, antenna is replaced by a leg)! !- genes required for ap axis in embryo! Nusslein-volhard, screened for sets of genes encoding morphogens for a, p, terminal regions. Bicoid, observed in gradient, high in anterior, low in posterior -> direction.
