Chapter 6

Question 1

a membrane with 2 molecular layers

Answer 1

bilayer

Question 2

the predominant sterol of animal cell membranes

Answer 2

cholesterol

Question 3

a protein embedded in the cell membrane that forms a channel allowing selected polar molecules and ions to pass across the membrane

Answer 3

transport proteins

Question 4

protein in the plasma membrane that identifies a cell as part of the same individual or as foreign

Answer 4

recognition proteins

Question 5

protein that recognizes and binds molecules from other cells that act as chemical signals

Answer 5

receptor proteins

Question 6

protein that binds cells together by recognizing and binding receptors or chemical groups on other cells or on the extracellular matrix

Answer 6

cell adhesion proteins

Question 7

a lipid molecule with carbohydrate groups attached

Answer 7

glycolipids

Question 8

protein with carbohydrate groups attached

Answer 8

glycoproteins

Question 9

a carbohydrate coat covering the cell surface

Answer 9

glycocalyx

Question 10

model proposing that the membrane consists of a fluid phospholipid bilayer in which proteins are embedded and float freely

Answer 10

fluid mosaic model

Question 11

protein embedded in a phospholipid bilayer

Answer 11

integral proteins

Question 12

protein held to membrane surfaces by noncovalent bonds formed with the polar parts of integral membrane proteins or membrane lipids

Answer 12

peripheral proteins

Question 13

technique in which experimenters freeze a block of cells rapidly, then fracture the block to split the lipid bilayer and expose the hydrophobic membrane interior

Answer 13

freeze-fracture technique

Question 14

the controlled movement of ions and molecules from one side of a membrane to the other

Answer 14

transport

Question 15

the transport of substances across cell membranes without expenditure of energy, as in diffusion

Answer 15

passive transport

Question 16

the mechanisms by which ions and molecules move against the concentration gradient across a membrane from the side with the lower concentration to the side with the higher concentration

Answer 16

active transport

Question 17

the net movement of ions or molecules from a region of higher concentration to a region of lower concentration

Answer 17

diffusion

Question 18

a difference in concentration molecules or ions between 2 areas

Answer 18

concentration gradient

Question 19

membranes that selectively allow, impede, or block the passage of atoms and molecules

Answer 19

selectively permeable

Question 20

mechanism by which certain small substances diffuse through the lipid part of a biological membrane

Answer 20

simple diffusion

Question 21

mechanism by which polar and charged molecules diffuse across membranes with the help of transport proteins

Answer 21

facilitated diffusion

Question 22

transport protein that forms a hydrophilic channel in a cell membrane through which water, ions, or other molecules can pass, depending on the protein

Answer 22

channel proteins

Question 23

a specialized protein channel that facilitates diffusion of water through cell membranes

Answer 23

aquaporins

Question 24

ion transporter in a membrane that switches between open, closed, or intermediate states

Answer 24

gated channels

Question 25

transport protein that binds a specific single solute and transports it across the lipid bilayer

Answer 25

carrier proteins

Question 26

the passive transport of water across a selectively permeable membrane in response to solute concentration gradients, a pressure gradient, or both

Answer 26

osmosis

Question 27

a state of dynamic equilibrium in which the pressure of the solution on one side of a selectively permeable membrane exactly balances the tendency of water molecules to diffuse passively from the other side of the membrane due to a concentration gradient

Answer 27

osmotic pressure

Question 28

the effect a solution has on a cell when the solution surrounds it

Answer 28

tonicity

Question 29

solution containing dissolved substances at lower concentrations than the cells it surrounds

Answer 29

hypotonic

Question 30

the internal hydrostatic pressure within plant cells

Answer 30

turgor pressure

Question 31

solution containing dissolved substances at higher concentrations than the cells it surrounds

Answer 31

hypertonic

Question 32

conditions due to outward osmotic movement of water, in which plant cells shrink so much that they retract from their water

Answer 32

plasmolysis

Question 33

equal concentration of water inside and outside cells

Answer 33

isotonic

Question 34

the mechanism by which ions and molecules move against the concentration gradient across a membrane, from the side with the lower concentration to the side with the higher concentration

Answer 34

active transport

Question 35

an electrical voltage that measures the potential inside a cell membrane relative to the fluid just outside; it is negative under resting conditions and becomes positive during an action potential

Answer 35

membrane potential

Question 36

transport in which the same protein that transports a substance also hydrolyzes ATP to power the transport directly

Answer 36

primary active transport

Question 37

transport indirectly driven by ATP hydrolysis

Answer 37

secondary active transport

Question 38

pump that moves hydrogen ions across membrane and pushes hydrogen ions across the plasma membrane from the cytoplasm to the cell exterior

Answer 38

proton pumps/ H+ pump

Question 39

pump that pushes Ca2+ from the cytoplasm to the cell exterior, and also from the cytosol into the vesicles of the endoplasmic

Answer 39

Ca2+ pump

Question 40

pump that pushes 3 Na+ out of the cell and 2 K+ into the cell in the same pumping cycle

Answer 40

Na+/K+ pump

Question 41

a difference in chemical concentration and electric potential across a membrane

Answer 41

electrochemical gradient

Question 42

the transport of 2 molecules in the same direction across a membrane

Answer 42

symport

Question 43

a secondary active transport mechanism in which a molecule moves through a membrane channel into a cell and powers the active transport of a second molecule out of the cell

Answer 43

antiport/exchange diffusion

Question 44

mechanism by which extracellular water is taken into a cell together with any molecules that happen to be in solution in the water

Answer 44

bulk-phase endocytosis

Question 45

the selective uptake of macromolecules that bind to cell surface receptors concentrated in clathrin-coated pits

Answer 45

receptor-mediated endocytosis

Question 46

a depression in the plasma membrane that contains receptors for macromolecules to be taken up by endocytosis

Answer 46

coated pit

Question 47

the network of proteins that coat and reinforce the cytoplamic surface of cell membranes

Answer 47

clathrin

Question 48

process in which some types of cells engulf bacteria or other cellular debris to break them down

Answer 48

phagocytosis

Question 49

the outer limit of the cytoplasm responsible for the regulation of substances moving into and out of cells

Answer 49

plasma membrane