A(n) ________ is an example of Primary Active Transport.
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Diffusion
________ does not require energy nor binding to a transporter protein.
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Larger surface area
________ makes more opportunity for substances to permeate.
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Ions
________ can only move down a concentration gradient if channels are present in the plasma membrane.
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Polar
________ or charged molecules can not readily cross a cell membrane via simple diffusion.
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Ion channels
________ do not require binding.
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Ion channels
________ allow downhill movement of ions.
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Simple diffusion
Random movement of molecules due to thermal motion
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Net diffusion
Always occurs down a concentration gradient
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Flux
The amount of a substance crossing a membrane per unit time
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Net flux
The difference between two one-way fluxes
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Lipid bilayer
The limiting factor for diffusion across cell membranes
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Simple diffusion
The type of diffusion by while non-polar molecules readily move
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Electrochemical gradient
The net flux in and out of a cell is ultimately determined by this gradient
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Ligand-gated
Cell membrane channels that open on one side of the cell membrane to open or close to passage
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Voltage-gated
Channels that rely on electrical signals to move open or closed
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Mechanically-gated channels
Channels of a cell membrane that must move themselves open or closed using energy
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Leak
Non-gated cell membrane channels
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Osmosis
Net diffusion of water from a region of higher water concentration to a region of lower concentration
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Osmolarity
total moles of solute divided by Liters of solution
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Aquaporins
Channels that allow the rapid passage of water through the cell membrane, necessary because water is polar
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Permeable
If a membrane is fully to water and solute, both will eventually reach equilibrium
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Semi-permeable
If membrane is (only permeable to water), water will move to area of higher solute concentration
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Mediated transport
The process by which the solute moves by binding to a transmembrane protein known as a transporter
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Facilitated diffusion, active transport
Two broad categories of mediated transport
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Facilitated diffusion
A type of mediated transport that involves downhill movement, no energy required
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Active transport
A type of mediated transport that involves uphill movement and requires energy (ATP)
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Primary
This Active Transport type occurs when energy comes directly from ATP hydrolysis
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Secondary
This Active Transport type occurs when energy comes from an existing ion gradient
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Cotransport
A type of secondary active transport; Transported substance can move in same direction as Na+ and it kinda hitches a ride
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Countertransport
A type of secondary active transport; Transported substance can move in opposite direction as Na+ where it kinda sneaks against the sodium flow
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Endocytosis
Cell membrane folds in from the outside to create a baby pocket, losing some cell membrane and requiring ATP, and is generally used for bulk movement
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Exocytosis
Vesicle fuses to te cell membrane to release stuff outside of the cell; replaces the membrane it lost during endocytosis; most secreted substances come from the Golgi apparatus
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