simple diffusion
when a substance goes directly through the bilayer
gradient
differences in concentration
passive transport
no energy is needed, move from a high to low concentration
diffusion
movement that goes with the gradient
tonicity
ability of a surrounding solution to gain or lose water
facilitated diffusion
substances require a protein transporter to be able to cross the membrane
active transport
energy is required, substances move against the concentration gradient
uniporter
a protein transporter that pumps one substance across a membrane
cotransporter
a protein transporter that pumps several substances across a membrane
antiporter
a protein transporter that moves substances in opposite directions
symporter
a protein transporter that moves substances in the same direction
coupled transport
a gradient that is made by a uniporter, is used to move substances through a cotransporter
endocytosis
when materials are internalized by a cell through engulfing
phagocytosis
engulfs large solid particles
pinocytosis
engulfs a portion of something, taking in dissolved contents in bulk
receptor-mediated endocytosis
when a membrane is lined with receptors that bind to specific materials and move in bulk
clathrin-coated pits
areas where receptors are found
isotonic
movement in and out of cells is =
hypotonic
movement into the cell
hypertonic
movement out of the cell
osmoregulation
the attempt to maintain a proper water balance
selectively permeable membrane
only let in certain molecules based on their size and polarity
transcytosis
substances enter, move through, then exit a cell