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Selective Permeability
- Allo some substance to cross plasma membrane more easily
- Polar substance like glucose and water pass slower than nonpolar like oxygen ,co2 and hydrogencarbon
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Amphipathic
- have both hydrophililic region and a hydrophobic region.
- Ex: phopholipid and other membranes
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Fluid Mosaic Model
Model of plasma membrane
Phospholipid bilayer heads, hydrophobic tail inside, Hyrophoci region between the heads
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Integral proteins
membrane prteins that penetratr the hydrophobic interior of lipid bilaye
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Peripheral Proteins
- no embedded in the lipid bilayer
- loosely bound to the surface of the membrane
- exposed to part of intergral proteins
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Functions of plasma membrane proteins
- Transport
- Enzymatic activity
- Signal transduction
- cell cell recognition
- intercellular joining
- attachment to the cytoskeleton and ECM
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Transport Protein
channel protein, hydrophilic channel that certain molecukes use it as tunnel through the membrane
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Diffusion
- the movement of molecules of any substance so that they spread out evenly into avaliable space
- concentration gradient - substance diffuse down
- no work is needed
- passive transport - no energy
- active transport - yses energy
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Osmosis
the diffusion of free water across a selectively permeable membrane
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tonicity/isotonic/hypertonic
- the ability of a surrounding solution to cause a cell to gain or lose water
- isotonic - same , no net movement of the water
- hypertonic - cell lose water, shrivel, and probably die
- hypotonic into cell - water enter cell fast make it swell and lyse(burst)
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plasmolysis
plant cell place in a hypertonic environment -> CELL SHRIVELS and lose water to surrounding -> die
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Membrane potential
voltage across a membrane
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cotransport
single ATP powered pump that transports a specific solutes in a mechanism called a cotransport.
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exocytosis
cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane
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endocytosis
the cell takes in biological molecules and particulate matter by forming new vesicles from the plasm membrane
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