Membrane Transport
Terms
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- Filtration
- physical pressure forces molecule through membrane
- Simple diffusion
- movement of particles from high to low concentration
- Osmosis
- Simple diffusion of H2O
- Membrane Transport
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-Selectively permeable: Allows some substances to pass
-Only small uncharged molecules or fat soluble molecules can pass through membrane w/out help
-other molecules require "help"- proteins in plasma membrane can form channels or pumps to help other molecules pass through. - Facillitated diffusion
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carrier mediated transport
-form channels - Active Transport
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expenditure of energy (ATP) to move solute across membrane UP concentration gradient
-pumps - Endocytosis
- into the cell. Membrane invaginates and forms a vesicle. Three types (phagocytosis, pinocytosis, and receptor mediated endocytosis)
- phagocytosis
- "cell eating" membranous vesicle is called "phagosome" Fuses w/ a lysosome-acts as the "stomach" of the cell.
- Pinocytosis
- "Cell Dringking" plasma membrane surrounds a tiny bit of extracellular fluid. Pinocytotic vesicle
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Vesicular Transport
(Exocytosis) - Out of the cell. Substanse to be released is first enclosed in a membrane-walled sac or vesicle. Migrates to membrane and fuses w/ it to dump out contents.