Ch. 7 Vocab

Question 1

a region along which the density of a chemical substance increases or decreases

Answer 1

concentration gradient

Question 2

channel proteins in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis; the diffusion of water across the membrane

Answer 2

aquaporins

Question 3

the movement of a substance across a cell membrane with an expenditure of energy, against its concentration or electrochemical gradient; mediated by specific transport proteins

Answer 3

active transport

Question 4

having both a hydrophilic region and a hydrophobic region

Answer 4

amphipathic

Question 5

the spontaneous movement of a substance down its concentration gradient, from a region where it is more concentrated to a region where it is less concentrated

Answer 5

diffusion

Question 6

the cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

Answer 6

exocytosis

Question 7

an ion transport protein that generates voltage across a membrane

Answer 7

electrogenic pump

Question 8

the diffusion gradient of an ion, which is affected by both the concentration difference of the ion across a membrane (a chemical force) and the ion’s tendency to move relative to the membrane potential (an electric force)

Answer 8

electrochemical gradient

Question 9

the currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

Answer 9

fluid mosaic model

Question 10

limp; lacking in stiffness or firmness, as in a plant cell in surroundings where there is no tendency for water to enter the cell

Answer 10

flaccid

Question 11

the spontaneous passage of molecules or ions across a biological membrane with the assistance of specific transmembrane transport proteins

Answer 11

facilitated diffusion

Question 12

cellular uptake of biological molecules and particulate matter via formation of new vesicles from the plasma membrane

Answer 12

endocytosis

Question 13

the coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own concentration gradient

Answer 13

cotransport

Question 14

lipids with covalently attached carbohydrates

Answer 14

glycolipids

Question 15

a protein with one or more carbohydrates covalently attached to it

Answer 15

glycoproteins

Question 16

transmembrane protein channels that open or close in response to a particular stimulus

Answer 16

gated channels

Question 17

referring to a solution that, when surrounding a cell, will cause the cell to take up water

Answer 17

hypotonic

Question 18

referring to a solution that, when surrounding a cell, will cause the cell to lose water

Answer 18

hypertonic

Question 19

transmembrane protein channels that allow a specific ion to flow across the membrane down its concentration gradient

Answer 19

ion channels

Question 20

typically a transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on either side of the membrane (or lining the channel in the case of a channel protein)

Answer 20

integral proteins

Question 21

referring to a solution that, when surrounding a cell, has no effect on the passage of water into or out of the cell

Answer 21

isotonic

Question 22

a molecule that binds specifically to another molecule, usually a larger one

Answer 22

ligands

Question 23

a type of endocytosis in which large particulate substances are taken up by a cell

Answer 23

phagocytosis

Question 24

a phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment

Answer 24

plasmolysis

Question 25

the diffusion of a substance across a biological membrane with no expenditure of energy

Answer 25

passive transport

Question 26

proteins loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer

Answer 26

peripheral proteins

Question 27

an active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process

Answer 27

proton pump

Question 28

a type of endocytosis in which the cell ingests extra cellular fluid and its dissolved salutes

Answer 28

pinocytosis

Question 29

the diffusion of water across a selectively permeable membrane

Answer 29

osmosis

Question 30

regulation of solute concentrations and water balance by a cell or organism

Answer 30

osmoregulation

Question 31

a property of biological membranes that allows them to regulate the passage of substances

Answer 31

selective permeability

Question 32

transmembrane proteins that help a certain substance or class of closely related substances to cross the membrane

Answer 32

transport proteins

Question 33

swollen or distended, as in plant cells

Answer 33

turgid

Question 34

a transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell

Answer 34

sodium-potassium pump