IBIO 425 Study Guide - Final Guide: Clathrin, Nuclear Membrane, Extracellular Fluid
Document Summary
Micro-endocytosis of extracellular fluid containing soluble substances and small particles within pinocytotic "smooth" (no clathrin) vesicles ("calveolae) Extracellular molecules bind to specific pm receptors concentrated in local microdomains (lipid rafts) This induces their aggregation into "coated pits" medicated by clathrin proteins on the internal pm surface. These pits are internalized as "coated vesicles (endosomes) which are targeted to fused with specific organelles. Endocytosis of particles (bacteria, cell debris), typically by macrophages and granulocytes (both are wbc) Fc receptors on macrophage pm recognize fc tail of antibodies bound to foreign antigen. Internalized phagosome subsequently fuses with primary lysosome in cyotplasm leading to hydrolytic degradation of its biological contents by lysosomal enzynes. Snare-mediated fusion of intracellular vesicle membranes with pm yields either constitutive or regulated (hormone- or neurotransmitter-triggered) secretion. Vesicles contents are released (secreted_ into extrenal environment but vesicles membrane is retained. Structure housing genetic machinery which controls cell activity.
