18 terms

Biology Chapter 4

molecules that make the membrane fluid
enzymes, receptors, transporters
3 roles of membrane proteins
role of carbohydrates attached to some proteins
cholesterol; keep membrane fluid
molecules that are buried in the membrane; only found in animal cell membranes
holds cell's contents together, identifies the cell, controls what enters/leaves the cell
3 roles of the plasma membrane
passive transport
movement across the cell membrane that does not require energy from the cell
concentration gradient
difference in the concentration of a substance across a space
a condition in which the concentration of a substance is equal throughout the space
the movement of a substance from an area of high concentration to an area of lower concentration caused by the random motion of particles of the substance
the diffusion of water through a selectively permeable membrane
hypertonic solution
a solution that causes a cell to shrink due to osmosis
hypotonic solution
a solution that causes a cell to swell because of osmosis
isotonic solution
a solution that produces no change in cell volume because of osmosis
ion channel
a transport protein with a polar pore through which ions can pass
sodium-potassium pump
a protein that actively transports sodium ions and potassium ions against their concentration gradient
active transport
the transport of a substance across the cell membrane against its concentration gradient
the movement of a substance into a cell by a vesicle
the movement of a substance by a vesicle to the outside of a cell