BIO230H1 Lecture Notes - Lecture 17: Sonic Hedgehog, Chromosome, Morphogen
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BIO230H1 Full Course Notes
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Two main mechanisms of cell differentiation: asymmetric division-sister cells born different. Asymmetric cell divisions to form the gut. Li(cid:374)eage trees (cid:272)a(cid:374) sho(cid:449) ho(cid:449) (cid:272)ells (cid:862)gro(cid:449) up(cid:863) When the cell begins to split, the proteins will localize to one side or the other. When cell divides, one cell will get all of one protein, other cell (cid:449)o(cid:374)"t get a(cid:374)(cid:455) of that protei(cid:374) Pull apart by spindle allingment and asymmetric determinants. If cell is(cid:374)"t alig(cid:374)ed properl(cid:455), it (cid:449)o(cid:374)"t (cid:449)ork: symmetric division-sister cell becomes different as a result of external influences after birth, aka extrinsic mechanisms of cell differentiation. One cell is exposed to a particular protein and will change, while the other (cid:272)ell (cid:449)o(cid:374)"t. Cells begin equal, some cells gain an advantage: randomly differentiated. Cells differentiate and inhibit neighbours from differentiating. Inhibits nieghbours from doing the same: generally, cells have no specialization, no delta, and active. Notch, if notch is inactive, then will get delta and will specialize: overall-competition between neighbours.
