Quiz Two Flashcards
diffusion
when molecules move from an area of high concentration to an area of low concentration (following a gradient)
what is passive transport?
when materials enter or exit a cell without the cell having to exert any energy (molecules flow from areas of high concentration to areas of low concentration following the natural gradient)
what are the 3 forms of passive transport?
diffusion, osmosis, facilitated diffusion
inorder to defuse across a cell membrane, what characteristics to molecules need to have
they need to be small and non polar. they must behave like lipids, as the tails of the lipid bilayer are hydrophobic, and even when they are not polar, they must be small enough to fit through the membrane
how does the gradient change as molecules diffuse?
the closer to equilibrium, the less dramatic the gradient
why can water, a non polar molecule, still diffuse across cell membranes?
it is so tiny that it can squeeze past the lipid bilayer
what are the characteristics of the lipid bilayer?
lipids are generally hydrophobic or water hating
the heads of the phospholipids however are hydrophilic or water loving
the tails are hydrophobic
osmosis
a special term for the diffusion of water molecules
what does it mean the the membrane is “permeable to the solute”?
the solute is able to pass through the cell membrane
equilibrium
the concentration of whatever is diffusing is equal inside and outside of the cell. there is no further net change
hypertonic
has less solute and therefore a higher concentration of solvent, causing the solvent to move out of the cell
when a lot of the solvent moves from the cell, the cell crinkles and is referred to as crenate
isotonic
(normal)
there is an equal concentration of solute inside and outside of the cell, equilibrium
hypotonic
there is a higher concentration of solute inside of the cell, leading solute to come into the cell, causing the cell to swell
do the terms hypo and hyper tonic refer to the concentration of the solute or of the solvent?
they refer to the concentration of the solute
facilitated diffusion
-passive transport
-diffusion allows the molecules to get through the channel
-Proteins form tunnels or channels-
they are specific gates, they are specific to certain molecules only allowing specific molecules through
-protein channels are used to transport molecules not permeable to the cell membrane
