Lecture 14 11

Lecture 14 11 - Lecture 14 11/05/07 Endocytosis Endocytosis...

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Lecture 14 11/05/07 Endocytosis Endocytosis – Transport into the cell -3 kinds: Phagocytosis Pinocytosis Caveolae Phagocytosis – engulf food Bulk uptake/cell eating How cells take in large macromolecules Immune system response: o Animal cells use phagocytosis as part of the immune response to defend against microorganisms White blood cells: 1.) Macrophages – responds to chronic infection 2.) Neutrophils – acute infection 3.) dendritic cells – responds only if given specific cue from immune system (e.g. Antibody on surface of bacterial cell) Protozoa use phagocytosis Phagosome – large vesicle, merges with lysosome to make: phagolysosome Steps for Phagocytosis 1.) Chemotaxis- chemical signal -movement of cell that is going to be phagocytosing a particle toward a chemical attractant that is displayed on the prey 2.) Adherence of prey 3.) Pseudopodia formation- “false feet” -protrusion from cell that does phagocytosis 4.) Engulfment of prey -aka phagosome formation -feet completely surround prey large vesicle formed 5.) Formation of phagolysosome -pH decreases so that phagosome can fuse with lysosome -proton pumps to decrease pH are ATP dependent Cells have signal that is recognized by the cell and is required o These signals prevents the cell from eating themselves up Antibodies – well characterized Inhibitory signal – “do not eat me,” designates self object, bind to receptor on phagocyte surface -need inhibitory signal (necessary)
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-Ex: small glass beads don’t have this signal so they will be engulfed Bacteria that use phagocytosis to their advantage -some bacteria found a way to survive using phagocytosis, usually they somehow prevent fusion with lysosome and are able to replicate in host cell 1) Samonella – phagocytosed but no fusion of phagosome with lysosome, because it secretes a protein that prevents fusion
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This note was uploaded on 07/21/2008 for the course BICD 110 taught by Professor Mel during the Fall '06 term at UCSD.

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Lecture 14 11 - Lecture 14 11/05/07 Endocytosis Endocytosis...

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