BIO 320 - CELL BIOLOGYT. O'Halloran & A. De LozanneLecture 9 (02/16/2010).Endocytosis And ExocytosisReading: Alberts, 5th Ed. Pages 799-809 Endocytosis: Cellular Uptake of Particles and MacromoleculesA. Phagocytosis is the cellular uptake of particulate matter from the environment.B. Endocytosis is the cellular uptake of material dissolved or suspended in fluid.1. Bulk-phase endocytosis does not require binding to the surface membrane.2. Receptor-mediated endocytosis (RME) follows the specific binding of substancesto membrane receptors.a. Ligand-bound receptors collect in specialized regions of the membrane forming coated pits. The sorting signal appears to be a key tryosine in the cytoplasmic tail of receptors.b. Clathrin-coated regions invaginate into the cytoplasm, forming coated vesicles.c. Clathrin contains three chains that form a triskelion capable of changing from a flat sheet to a cage like scaffold surrounding the vesicle.
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