BIO230H1 Lecture Notes - Lecture 17: Morphogen, Lateral Inhibition, Hox Gene
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BIO230H1 Full Course Notes
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Extrinsic mechanisms of cell differentiation: direct lateral inhibition, creates patterns of isolated differentiated cells. All cells begin equal; some cells randomly gain an advantage; these cells differentiate and inhibit their neighbours from differentiating: eg. Notch signalling: delta activates notch in a neighbouring cell (both transmembrane proteins, notch activation inhibits cell specialization; notch activation also inhibits. Delta expression: one cell with an active delta specializes eventually and inhibits its neighbours, eg. Secreted inductive molecules that spread in a gradient: morphogen concentration in the gradient often dictate the effect on cell fate, ie. high, intermediate and low concentration can initiate different developmental programs in surrounding cells, organizer tissues. Black cells organizer cells (ie. secretes morphogens; is the source: grey cells just respond to morphogens. Grey cells : organizer function in vertebrate limb development, this example is a polarizing region (ie. makes the ends of the wings different); however, not all organizer tissues are polarizing, eg.
