CSB328H1 Lecture Notes - Lecture 19: Prostomium, Morphogen, Telson
28 Nov 2016
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Document Summary
Morphogen: molecule that can make a gradient and cells can respond to that gradient. Bicoid protein is a morphogen: % egg length vs bicoid concentration graph. In the very anterior region of embryo, there is a high concentration of bicoid mrna because it is a maternal determinant. 50% to 70% egg length is between threshold 1 and 2. A higher threshold is needed to make head structures. Bicoid is a transcription factor that regulates certain genes: target genes are the gap genes (called gap genes because wen you look at the mutants, there are certain gaps in the pattern/certain elements are missing) Mutant: defects in the thoracic region/elements are missing. Hb and otd may respond to different thresholds in the gradient (due to their mutations: low concentration of bicoid is sufficient to activate hunchback expression. Everywhere between 50% and 100% hunchback can be expressed: otd responds to a much higher concentration of bicoid.
