Vocabulary Chapter 5
5.1 Passive Transport
passive transport: substances crossing the cell membrane without any input of energy by the cell
diffusion: movement of molecules from an area of higher concentration to lower concentration
concentration gradient: a difference in the concentration of a substance across a distance
equilibrium: when the concentration of a substance is the same throughout a space
osmosis: process when water molecules diffuse across a cell membrane from an area of higher concentration to lower concentration
hypotonic: a solution whose solute concentration is lower than the solute concentration inside a cell
hypertonic: a solution whose solute concentration is higher than the solute concentration inside a cell
isotonic: when the concentrations of solutes outside and inside the cell are equal
contractile vacuoles: organelle in fresh water organisms (like paramecium) that collects excess water and pumps it out of the cell.
cytolysis: bursting of a cell
facilitated diffusion: a type of passive transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins
carrier proteins: protein that transports substances across a cell membrane
ion channels:protein molecules in a cell membrane that form a pore through which ions can pass
5.2 Active Transport
active transport: movement of chemical substances against a concentration gradient; requires cell to use energy
sodium-potassium pump:carrier protein that uses ATP to actively transport sodium and potassium ions against their concentration gradient: sodium is pumpedout of a cell and potassium is pumped into the cell.
endocytosis: process by which a cells ingest other materials (fluids, macromolecules, large particles). The cell membrane surrounds a particle and encloses the material in a vesicle to bringit into the cell.
vesicle: sac which forms when part of the cell membrane surrounds the materials to be taken into or transported within the cell
pinocytosis: type of active transport across the cell membrane where the cell takes in fluids
phagocytosis:process by which a cell engulfs large particles or whole cells, either as a defense mechanism or to obtain food
exocytosis:process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out.