BIO230H1 Lecture Notes - Lecture 5: Morphogen, Sonic Hedgehog, Lateral Inhibition
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BIO230H1 Full Course Notes
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Extrinsic mechanism: signal from the outside go into the cell, affecting the phenotype. Asymmetric cell division and cell differentiation in c. elegans. Asymmetric cell division partitions cell fate determinants to define the germline and other tissues. Requires asymmetric determinants (asymmetrically positioned) and proper spindle alignment. Creates a pattern of isolateral differentiated cells. E. g. neurons have to be distributed evenly and spread out. Inhibitory binding of delta to notch notch sends signal into the cell, blocking the cell"s ability to differentiate and inhibit other cells. String d-n sugalling inhibit the cell. Fly sensory bristle development provides a model for studying lateral inhibition. This patch of cells all differentiated into bristle-producing cells. Extrinsic mechanisms of cell differentiation: induction by diffusible signals. A diffusible signal from a group of cells drives neighboring groups into distinct developmental pathways. The effects depend on the distance between the target group and the signal source.
