aos 1- biology Flashcards
passive transport
-requires no energy
-the movement of molecules from high to low concentration;moves with the concentration gradient
concentration gradient
a difference in the concentration of a substance across a distance
equilibrium
the concentration of molecules is equal throughout the space
diffusion
movement of molecules from an area of higher concentration to an area of lower concentration, down the gradient across a semi-permeable membrane
osmosis
diffusion of water down its concentration gradient through a selectively permeable membrane
hypertonic solution
a solution in which the concentration of solutes is greater outside the cell than inside the cell or the concentration of the water is greater on the inside of the cell
hypotonic solution
a solution in which the concentration of solutes outside the cell is less than the inside of the cell or the concentration of water is greater on the outside of the cell
isotonic solution
a solution outside the cell whose solute concentration is equal to the solute concentration inside the cell
carrier protein
a protein that transports specific substances across the cell membrane
facilitated diffusion
another type of passive transport, used for molecules that cannot readily diffuse the cell membranes. Use carrier proteins
active transport
the energy-requiring process that moves materials across the cell against a concentration difference
sodium-potassium pump
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell
endocytosis
active transport processes where a cell engulfs materials with a proportion f the cells plasma membrane and releases the contents inside of the cell
exocytosis
a process in which a vesicle inside a cell fuses with the cell membrane and releases its contents to the external environment. Transports to outside of the cell
selectively permeable
a property of cell membranes that allows some substances to pass through while others cannot
