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Biology 125 Exam 3- IWU

Terms in this set (82)

Selective Permeability
Allowing some substances to cross it more easily than other
Amphipathic Molecules
Containing hydrophobic and hydrophilic regions
Aquaporins
channel proteins for facilitated diffusion of water
Diffusion
The tendency for molecules to spread out evenly into available space
how membrane fluidity is influenced by temperature and membrane composition
Cooler temperature means less fluid; lipid composition determines the temperature at which the membrane solidifies
Peripheral membrane proteins
on the membrane surface
Channel and Carrier Proteins
____________ proteins use corridors, aquaporins are used to facilitate diffusion of water; ________ proteins undergo a subtle change in shape, the bound solute is translocated across the membrane
Passive diffusion
the tendency for molecules to spread out evenly into available space, substances diffuse down their concentration of a substance from one area to another
Osmosis
the diffusion of water across a selectively permeable membrane, water diffuses from low solute concentration-->high solute concentration
Facilitated diffusion
requires transport proteins, transport proteins allow passage of specific hydrophilic substances, speeding the passive movement of molecules across the membrane
Active transport
requires energy, moves solutes against their concentrated gradient, specific proteins in the membrane perform active transport; ATP is usually the energy source [low] --> [high]
Secondary active transport
occurs when active transport of a solute indirectly drives the transport of another solute, plants commonly use the gradient of hydrogen ions generated by proton pumps to drive active transport of nutrients into the cellHypertonic solution
Hypertonic solution
solute concentration is greater than that inside the cell; cell loses water
Hypotonic solution
solute concentration is less than that of inside the cell; cell gains water
Isotonic solutions
solute concentration is the same as that inside the cell; no net water movement across the plasma membrane
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