Cell Biology

... from active transport to vesicles

phagocytosis

Phagocytosis involves the sporadic engulfment of large extracellular particles by wrapping cytoskeletally supported pseudopodia around the particle and internalizing it into vacuoles called phagosomes. The phagosome then fuses with a lysosome, forming a phagolysosome, and the phagocytosed particle is digested in an oxidative burst by lysosomal enzymes. The hydrolyzed products are assimilated by absorption into the cytoplasm through the vacuolar wall, and the waste products are excreted from the cell.

Phagocytosis is performed by unicellular organisms such as Paramecia and by specialized phagocytes in multicellular organisms.

In some instances, phagocytosis does not result in the destruction of phagocytozed bacteria – this mechanism is considered responsible for serial endosymbiosis. Endosymbiotic bacteria have been experimentally observed to undergo endosymbiotic gene transfer.

[] image_Paramecium feeding on hematococcus [] phagocytic embrace [] macrophage attacking bacterium [] sem Macrophage [] sem "walking macrophage" [] sem activated macrophage phagocytosing bacteria [] sem alveolar macrophage attacking E. coli Џ animation - phagocytosis Џ animated diagram - phagocytosis of bacterium Џ time-lapse movie - phagocytosis Џ animation - exocytosis Џ

• A • adhesion • C • cell membranescellular adhesion moleculescellular signal transductioncentrioleschemotaxischloroplastcilia & flagellacommunicationconcentration gradientscytokine receptorscytoplasmcytoskeleton • E • energy transducersendoplasmic reticulumendosomesexosome • F • flagella & cilia • G • Golgi apparatusGPCRs • H • hormones • I • ion channels • L • lysosome • M • meiosismicrotubulesmitosismitochondrion • N • Nitric Oxideneurotransmissionneuronal interconnectionsnuclear membranenuclear pore • P • pinocytosisproteasomepumps • R • receptor proteinsreceptor-mediated endocytosis • S • second messengerssignaling gradientssignal transductionspindlestructure • T • transporttwo-component systems • V • vacuolevesicle

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